Tuesday, May 3, 2011

WASTE WATER DISPOSAL SYSTEMS; FIXTURES AND FITTINGS; PUMPING SYSTEMS; SEPTIC TANKS; SOAK PITS; MANHOLES

AR-461: BUILDING SCIENCE
By:
RAVINDAR KUMAR
Assistant Professor
Department of Architecture and Planning
NED University of Engineering and Technology
Karachi
LECTURE NO. 28
TOPIC:             WASTE WATER DISPOSAL SYSTEMS; FIXTURES AND FITTINGS; PUMPING SYSTEMS; SEPTIC TANKS; SOAK PITS; MANHOLES

INTRODUCTION
Wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. In the most common usage, it refers to the municipal wastewater that contains a broad spectrum of contaminants resulting from the mixing of wastewaters from different sources. Sewage is correctly the subset of wastewater that is contaminated with feces or urine, but is often used to mean any waste water. "Sewage" includes domestic, municipal, or industrial liquid waste products disposed of, usually via a pipe or sewer or similar structure, sometimes in a cesspool emptier. The physical infrastructure, including pipes, pumps, screens, channels etc. used to convey sewage from its origin to the point of eventual treatment or disposal is termed sewerage.

ORIGIN OF WASTE WATER:
Wastewater or sewage can come from (text in brackets indicates likely inclusions or contaminants):

  1. Human waste (fæces, used toilet paper or wipes, urine, or other bodily fluids), also known as blackwater, usually from lavatories;
  2. Cesspit leakage;
  3. Septic tank discharge;
  4. Sewage treatment plant discharge;
  5. Washing water (personal, clothes, floors, dishes, etc.), also known as greywater or sullage;
  6. Rainfall collected on roofs, yards, hard-standings, etc. (generally clean with traces of oils and fuel);
  7. Groundwater infiltrated into sewage;
  8. Surplus manufactured liquids from domestic sources (drinks, cooking oil, pesticides, lubricating oil, paint, cleaning liquids, etc.);
  9. Urban rainfall runoff from roads, carparks, roofs, sidewalks, or pavements (contains oils, animal fæces, litter, fuel or rubber residues, metals from vehicle exhausts, etc.);
  10. Seawater ingress (high volumes of salt and micro-biota);
  11. Direct ingress of river water (high volumes of micro-biota);
  12. Direct ingress of manmade liquids (illegal disposal of pesticides, used oils, etc.);
  13. Highway drainage (oil, de-icing agents, rubber residues);
  14. Storm drains (almost anything, including cars, shopping trolleys, trees, cattle, etc.);
  15. Blackwater (surface water contaminated by sewage);
  16. Industrial waste
  17. industrial site drainage (silt, sand, alkali, oil, chemical residues);
    1. Industrial cooling waters (biocides, heat, slimes, silt);
    2. Industrial process waters;
    3. Organic or bio-degradable waste, including waste from abattoirs, creameries, and ice cream manufacture;
    4. Organic or non bio-degradable/difficult-to-treat waste (pharmaceutical or pesticide manufacturing);
    5. extreme pH waste (from acid/alkali manufacturing, metal plating);
    6. Toxic waste (metal plating, cyanide production, pesticide manufacturing, etc.);
    7. Solids and Emulsions (paper manufacturing, foodstuffs, lubricating and hydraulic oil manufacturing, etc.);
    8. Agricultural drainage, direct and diffuse.

WASTEWATER CONSTITUENTS:
The composition of wastewater varies widely. This is a partial list of what it may contain:

  1. Water ( > 95%) which is often added during flushing to carry waste down a drain;
  2. Pathogens such as bacteria, viruses, prions and parasitic worms;
  3. Non-pathogenic bacteria;
  4. Organic particles such as feces, hairs, food, vomit, paper fibers, plant material, humus, etc.;
  5. Soluble organic material such as urea, fruit sugars, soluble proteins, drugs, pharmaceuticals, etc.;
  6. Inorganic particles such as sand, grit, metal particles, ceramics, etc.;
  7. Soluble inorganic material such as ammonia, road-salt, sea-salt, cyanide, hydrogen sulfide, thiocyanates, thiosulfates, etc.;
  8. Animals such as protozoa, insects, arthropods, small fish, etc.;
  9. Macro-solids such as sanitary napkins, nappies/diapers, condoms, needles, children's toys, dead animals or plants, etc.;
  10. Gases such as hydrogen sulfide, carbon dioxide, methane, etc.;
  11. Emulsions such as paints, adhesives, mayonnaise, hair colorants, emulsified oils, etc.;
  12. Toxins such as pesticides, poisons, herbicides, etc.
  13. Pharmaceuticals and other hormones.

SEWAGE:
Sewage is water-carried wastes, in either solution or suspension, that is intended to flow away from a community. Also known as wastewater flows, sewage is the used water supply of the community. It is more than 99.9% pure water and is characterized by its volume or rate of flow, its physical condition, its chemical constituents, and the bacteriological organisms that it contains. Depending on their origin, wastewater can be classed as sanitary, commercial, industrial, agricultural or surface runoff.

The spent water from residences and institutions, carrying body wastes, washing water, food preparation wastes, laundry wastes, and other waste products of normal living, are classed as domestic or sanitary sewage. Liquid-carried wastes from stores and service establishments serving the immediate community, termed commercial wastes, are included in the sanitary or domestic sewage category if their characteristics are similar to household flows. Wastes that result from an industrial process or the production or manufacture of goods are classed as industrial wastes. Their flows and strengths are usually more varied, intense, and concentrated than those of sanitary sewage. Surface runoff, also known as storm flow or overland flow, is that portion of precipitation that runs rapidly over the ground surface to a defined channel. Precipitation absorbs gases and particulates from the atmosphere, dissolves and leaches materials from vegetation and soil, suspends matter from the land, washes spills and debris from urban streets and highways, and carries all these pollutants as wastes in its flow to a collection point.

Wastewater from all of these sources may carry pathogenic organisms that can transmit disease to humans and other animals; contain organic matter that can cause odor and nuisance problems; hold nutrients that may cause eutrophication of receiving water bodies; and can lead to ecotoxicity. Proper collection and safe, nuisance-free disposal of the liquid wastes of a community are legally recognized as a necessity in an urbanized, industrialized society.

"Sewage" and "Sewerage" may be used interchangeably in the USA but elsewhere they retain separate and different meanings - sewage being the liquid material and sewerage being the pipes, pumps and infrastructure through which sewage flows.

SEWAGE PUMPING:
Sewage pumping is normally done by a submersible pump.

This became popular in the early 1960s, when a guide-rail system was developed to lift the submersible pump out of the pump station for repair, and ended the dirty and sometimes dangerous task of sending people into the sewage or wet pit. Growth of the submersible pump for sewage pumping since has been dramatic, as an increasing number of specifiers and developers learned of their advantages.

Three classes of submersible pumps exist:

Smaller submersible pumps, used in domestic and light commercial applications, normally handle up to 55mm spherical solids and range from 0.75kW to 2.2kW.
Larger submersible pumps, handle 65mm and larger solids and normally have a minimum of 80mm discharge. They are generally used in municipal and industrial applications for pumping sewage and all types of industrial wastewater.
Submersible chopper pumps, which are used to handle larger concentrations of solids and/or tougher solids that conventional sewage pumps cannot handle. Chopper pumps are generally used in municipal and industrial wastewater applications and provide clog-free operation by macerating those solids that might clog other types of submersible pumps.
Submersible pumps are normally used in a packaged pump station where drainage by gravity is not possible. Vertical type sewage pumps have also been used for many years. They have the motor above the floor so work on the motor can be done without entering the sewage pit.


SEWAGE DISPOSAL:
In some urban areas, sewage is carried separately in sanitary sewers and runoff from streets is carried in storm drains. Access to either of these is typically through a manhole. During high precipitation periods a sanitary sewer overflow can occur, forcing untreated sewage to flow back into the environment. This can pose a serious threat to public health and the surrounding environment. Sewage may drain directly into major watersheds with minimal or no treatment. When untreated, sewage can have serious impacts on the quality of an environment and on the health of people. Pathogens can cause a variety of illnesses. Some chemicals pose risks even at very low concentrations and can remain a threat for long periods of time because of bioaccumulation in animal or human tissue.

SEWAGE TREATMENT:
There are numerous processes that can be used to clean up waste waters depending on the type and extent of contamination. Most wastewater is treated in industrial-scale wastewater treatment plants (WWTPs) which may include physical, chemical and biological treatment processes.
However, the use of septic tanks and other On-Site Sewage Facilities (OSSF) is widespread in rural areas, serving up to one quarter of the homes in the U.S. The most important aerobic treatment system is the activated sludge process, based on the maintenance and recirculation of a complex biomass composed by micro-organisms able to absorb and adsorb the organic matter carried in the wastewater. Anaerobic processes are widely applied in the treatment of industrial wastewaters and biological sludge. Some wastewater may be highly treated and reused as reclaimed water. For some waste waters ecological approaches using reed bed systems such as constructed wetlands may be appropriate. Modern systems include tertiary treatment by micro filtration or synthetic membranes.

After membrane filtration, the treated wastewater is indistinguishable from waters of natural origin of drinking quality. Nitrates can be removed from wastewater by microbial denitrification, for which a small amount of methanol is typically added to provide the bacteria with a source of carbon. Ozone Waste Water Treatment is also growing in popularity, and requires the use of an ozone generator, which decontaminates the water as Ozone bubbles percolate through the tank.

Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that the pollutant concentrations in the treated wastewater comply with the local and/or national regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes or oceans. Other Industrial processes that produce a lot of waste-waters such as paper and pulp production has created environmental concern leading to development of processes to recycle water use within plants before they have to be cleaned and disposed of.

REUSE OF WASTE WATER:
Treated wastewater can be reused as drinking water, in industry (cooling towers), in artificial recharge of aquifers, in agriculture (70% of Israel's irrigated agriculture is based on highly purified wastewater) and in the rehabilitation of natural ecosystems.

SOAK PITS:
A Soak Pit, also known as a soakaway or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from a Collection and Storage/Treatment or (Semi-) Centralized Treatment technology is discharged to the underground chamber from where it infiltrates into the surrounding soil.

The Soak Pit can be left empty and lined with a porous material (to provide support and prevent collapse), or left unlined and filled with coarse rocks and gravel. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater. In both cases, a layer of sand and fine gravel should be spread across the bottom to help disperse the flow. The soak pit should be between 1.5 and 4m deep, but never less than 1.5m above the ground water table. As wastewater (pre-treated greywater or blackwater) percolates through the soil from the Soak Pit, small particles are filtered out by the soil matrix and organics are digested by micro-organisms. Thus, Soak Pits are best suited to soils with good absorptive properties; clay, hard packed or rocky soils are not appropriate.

WHEN ARE SOAK PITS THE RIGHT SOLUTION?
Soak pits are a good way to eliminate stagnant run-off water from latrines and they are a good alternative to large or small cess pools.

MATERIALS FOR ONE SOAK PIT:

PVC PIPING: Usually around a meter per soak pit.  It depends on the distance from the middle of your pit to the outlet.  1m~ 1500CFA

COVER: We used sheets of plastic 1.5m*1m per soak pit.  They are sold in 2m*1m sheets at ~300CFA/meter.  Rice sacks and straw can also be used.

CEMENT:  A small amount is needed to crepe the inside of the latrine wall and floor around the pipe.  1 bag 5750-6000CFA, we used less than two bags for 50 soak pits.  We used the mortar mix of 4:1 sand to cement ration.

ROCKS: enough to fill a 1m*1m hole

SAND: enough to make cement mortar

TOOLS: Shovels, dabas, buckets (something to transport cement in maybe a wheelbarrow or another bucket), a sieve to clean sand if dirty, pick axes

ORGANIZING THE PROJECT:
In my village, we had a group of men who were my soak pit team.  Concessions agreed to pay 500CFA for each soak pit they got, dig their own hole, and collect for rocks.  Then, when the holes were ready, my team went around and filled the hole, stuck the piping in, covered the hole and cemented the area around the pipe inside the latrine.  We could do 10 in one day if the holes were dug and rocks were ready.

PROCEDURE:
1.      Pick latrines with wastewater coming out of it and determine if a hole can be dug there
2.      Dig the hole.  We tried shooting for 1m*1m*1m holes, but often we hit rock at around half a meter, so then we just made the hole wider or longer.
3.     Fill the hole in with rocks of various sizes.  The rocks should be big enough so that there is space between them for water to go.  The Hippo handbook recommends putting a thin layer of sand and or gravel at the bottom of the pit.  We did not do this, but I think it is recommended for soak pits with larger volumes of water to help with absorption.
4.      Place in the pipe.  The pipe should exit the latrine and end in the middle of your pit.  The end should be sitting on top of a flat rock, when the rock hits a flat surface it can spread out easily from there instead of constantly hitting and thus eroding a small, pointy rock.
5.       Place rocks around the pipe where it enter the pit so that it will be protected when covered.
6.    Cover the pit with plastic/rice sacks/straw and then dirt.  Make sure there is enough dirt and it is packed down well enough so that things will not get damaged when walked over.  We also covered the pipe, because my villagers were worried that donkeys or cows would walk across the pipe and crunch it.
7.      Cement the pipe into place in the outlet, covering the area around the wall and floor where the water exits the latrine. So that water will exit through the pipe and nowhere else.

LESSONS LEARNED FROM JASON BEACH, SIKASSO REGION, 2006-2008
A total of 175 soak pits were constructed since the conception of my soak pit project which began back in September or so.  All and all the project has gone very well.  At the beginning of the project, there was a work crew of ten workers.  They were supposed to work together in building all of the soak pits.  But six of the ten quit during the project stating that it was too much work.  In a way, this was a good sign because it proved to me that the remaining four workers are the men who are extremely motivated to do sanitation work. As for the soak pits themselves, I have run into very few problems.  Some of the soak pits were constructed poorly and because of this, the cavity that was next to the pipe which allowed water to openly flow has caved in.  This is going to be fixed wherever the problem has occurred. I have discovered a problem with the soak pits that were dug.  The pipes have become clogged with dirt on a very regular basis (this has also happened with some soak pits too but it is a problem that really can’t be avoided with soak pits if your latrine is made of mud.  The problem can be slowed down though if the latrine is swept regularly.)  The pipes are too long for one to unclog with a metal bar or other instrument.  So I have decided that having a covered drain leading to the pump soak pit is impractical.  Therefore, I will rip up the concrete covering and enclosing the top of the pipe.  This will allow the water to flow openly and if there is dirt or other debris in the drainage trench, it will be easily accessible and therefore easy to move.  I will have a screen put at the end of the trench where it meets the soak pit to keep dirt and trash from entering the soak pit, thus allowing the soak pit to work appropriately for a longer period of time.  But my homologue and I also need to meet with the chief of the village who can help us form pump committees who could then oversee the maintenance and upkeep of the pump areas on a daily basis.  It is only with this last detail will the community be able to keep the pump areas sanitized.   

SEPTIC TANK:
A septic tank is a key component of the septic system, a small-scale sewage treatment system common in areas with no connection to main sewage pipes provided by local governments or private corporations. (Other components, typically mandated and/or restricted by local governments, optionally include pumps, alarms, sand filters, and clarified liquid effluent disposal means such as a septic drain field, ponds, natural stone fiber filter plants or peat moss beds.) Septic systems are a type of On-Site Sewage Facility (OSSF). In North America, approximately 25% of the population relies on septic tanks; this can include suburbs and small towns as well as rural areas (Indianapolis is an example of a large city where many of the city's neighborhoods are still on separate septic systems). In Europe, they are generally limited to rural areas only.

The term "septic" refers to the anaerobic bacterial environment that develops in the tank and which decomposes or mineralizes the waste discharged into the tank. Septic tanks can be coupled with other on-site wastewater treatment units such as biofilters or aerobic systems involving artificial forced aeration.[1]

Periodic preventive maintenance is required to remove the irreducible solids which settle and gradually fill the tank, reducing its efficiency. In most jurisdictions this maintenance is required by law, yet often not enforced. Those who ignore the requirement will eventually be faced with extremely costly repairs when solids escape the tank and destroy the clarified liquid effluent disposal means. A properly maintained system, on the other hand, can last for decades or possibly even a lifetime.

DESCRIPTION OF SEPTIC TANK:
A septic tank generally consists of a tank (or sometimes more than one tank) of between 4000 - 7500 litres (1,000 and 2,000 gallons) in size connected to an inlet wastewater pipe at one end and a septic drain field at the other. These pipe connections are generally made via a T pipe which allows liquid entry and exit without disturbing any crust on the surface. Today, the design of the tank usually incorporates two chambers (each of which is equipped with a manhole cover) which are separated by means of a dividing wall which has openings located about midway between the floor and roof of the tank.

Wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested, reducing the volume of solids. The liquid component flows through the dividing wall into the second chamber where further settlement takes place, with the excess liquid then draining in a relatively clear condition from the outlet into the leach field, also referred to as a drain field or seepage field, depending upon locality.

The remaining impurities are trapped and eliminated in the soil, with the excess water eliminated through percolation into the soil (eventually returning to the groundwater), through evaporation, and by uptake through the root system of plants and eventual transpiration. A piping network, often laid in a stone filled trench (see weeping tile), distributes the wastewater throughout the field with multiple drainage holes in the network. The size of the leach field is proportional to the volume of wastewater and inversely proportional to the porosity of the drainage field. The entire septic system can operate by gravity alone, or where topographic considerations require, with inclusion of a lift pump. Certain septic tank designs include siphons or other methods of increasing the volume and velocity of outflow to the drainage field. This helps to load all portions of the drainage pipe more evenly and extends the drainage field life by preventing premature clogging.

An Imhoff tank is a two-stage septic system where the sludge is digested in a separate tank. This avoids mixing digested sludge with incoming sewage. Also, some septic tank designs have a second stage where the effluent from the anaerobic first stage is aerated before it drains into the seepage field.

Waste that is not decomposed by the anaerobic digestion eventually has to be removed from the septic tank, or else the septic tank fills up and undecomposed wastewater discharges directly to the drainage field. Not only is this bad for the environment, but if the sludge overflows the septic tank into the leach field, it may clog the leach field piping or decrease the soil porosity itself, requiring expensive repairs.

How often the septic tank has to be emptied depends on the volume of the tank relative to the input of solids, the amount of indigestible solids and the ambient temperature (as anaerobic digestion occurs more efficiently at higher temperatures). The required frequency varies greatly depending on jurisdiction, usage, and system characteristics. Some health authorities require tanks to be emptied at prescribed intervals, while others leave it up to the determination of the inspector. Some systems require pumping every few years or sooner, while others may be able to go 10–20 years between pumpings. Contrary to what many believe, there is no "rule of thumb" for how often tanks should be emptied. An older system with an undersized tank that is being used by a large family will require much more frequent pumping than a new system used by only a few people. Anaerobic decomposition is rapidly re-started when the tank re-fills.

A properly designed and normally operating septic system is odor free and, besides periodic inspection and pumping of the septic tank, should last for decades with no maintenance.

A well designed and maintained concrete, fibreglass or plastic tank should last about 50 years.

MANHOLE:
A manhole (alternatively utility hole, cable chamber, maintenance hole, inspection chamber, access chamber or confined space) is the top opening to an underground utility vault used to house an access point for making connections or performing maintenance on underground and buried public utility and other services including sewers, telephone, electricity, storm drains and gas. It is protected by a manhole cover, also known as a 'biscuit', a plug designed to prevent accidental or unauthorized access to the manhole. Those plugs are usually made of metal or constructed from precast concrete (especially in Europe). Manholes are usually outfitted with metal or polypropylene steps installed in the inner side of the wall to allow easy descent into the manhole.

Manholes are generally found in urban areas, in streets and occasionally under sidewalks. They are usually in circular shape to prevent accidental fall of the cover in the hole.

In rural and undeveloped areas, services such as telephone and electricity may be carried on pylons rather than underground.

REFERENCES:
[1] Wastewater; From http://en.wikipedia.org/wiki/Wastewater (Retrieved May 6, 2011)
[2] Sewage; From: http://en.wikipedia.org/wiki/Sewage (Retrieved May 6, 2011)
[3] Sewage_treatment; From: http://en.wikipedia.org/wiki/Sewage_treatment (Retrieved May 6, 2011)
[4] Soak Pits; From: http://www.akvo.org/wiki/index.php/Soak_Pit (Retrieved May 6, 2011)
[5] Soak Pits; From: http://kalanke.web.officelive.com/Soak_Pits.aspx (Retrieved May 6, 2011)
[6] Septic Tank; From: http://en.wikipedia.org/wiki/Septic_tank (Retrieved May 6, 2011)
[7] Manhole; From: http://en.wikipedia.org/wiki/Manhole (Retrieved May 6, 2011)

FIRE FIGHTING SYSTEMS

AR-461: BUILDING SCIENCE
By:
RAVINDAR KUMAR
Assistant Professor
Department of Architecture and Planning
NED University of Engineering and Technology
Karachi
LECTURE NO. 27
TOPIC:                                                FIRE FIGHTING SYSTEMS

INTRODUCTION:[1]
Fire protection is the study and practice of mitigating the unwanted effects of fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as well as the research and development, production, testing and application of mitigating systems. In structures, be they land-based, offshore or even ships, the owners and operators are responsible to maintain their facilities in accordance with a design-basis that is rooted in laws, including the local building code and fire code, which are enforced by the Authority Having Jurisdiction. Buildings must be constructed in accordance with the version of the building code that is in effect when an application for a building permit is made. Building inspectors check on compliance of a building under construction with the building code. Once construction is complete, a building must be maintained in accordance with the current fire code, which is enforced by the fire prevention officers of a local fire department. In the event of fire emergencies, Firefighters, fire investigators, and other fire prevention personnel called to mitigate, investigate and learn from the damage of a fire. Lessons learned from fires are applied to the authoring of both building codes and fire codes. In the United States, this term is used by engineers and code officials when referring only to active and passive fire protection systems, and does usually not encompass fire detection systems such as fire alarms or smoke detection.

GOALS OF FIRE PROTECTION:
Fire protection has three major goals:
  • Continuity of operations - on a public scale, this is intended to prevent the interruption of critical services necessary for the public welfare (e.g., a 911 emergency call center).
  • Property protection - on a public scale, this is intended to prevent area wide conflagrations. At an individual building level, this is typically an insurance consideration (e.g., a requirement for financing), or a regulatory requirement.
  • Life safety - the minimum standard used in fire and building codes

CLASSIFYING FIRES:
When deciding on what fire protection is appropriate for any given situation, it is important to assess the types of fire hazard that may be faced. Some jurisdictions operate systems of classifying fires using code letters. Whilst these may agree on some classifications, they also vary.

Below is a table showing the standard operated in Europe and Australia against the system used in the United States of America:


Type of Fire
Australia
European
North America
Fires that involve flammable solids such as wood, cloth, rubber, paper, and some types of plastics.
Class A
Class A
Class A
Fires that involve flammable liquids or liquefiable solids such as petrol/gasoline, oil, paint, some waxes & plastics, but not cooking fats or oils
Class B
Class B
Class B
Fires that involve flammable gases, such as natural gas, hydrogen, propane, butane
Class C
Class C
Fires that involve combustible metals, such as sodium, magnesium, and potassium
Class D
Class D
Class D
Fires that involve any of the materials found in Class A and B fires, but with the introduction of an electrical appliances, wiring, or other electrically energized objects in the vicinity of the fire, with a resultant electrical shock risk if a conductive agent is used to control the fire.
Class E1
(Class E) now no longer in the European standards
Class C
Fires involving cooking fats and oils. The high temperature of the oils when on fire far exceeds that of other flammable liquids making normal extinguishing agents ineffective.
Class F
Class F
Class K


Technically there is no such thing as a "Class E" fire, as electricity itself does not burn. However it is considered a dangerous and very deadly complication to a fire, therefore using the incorrect extinguishing method can result in serious injury or death. Class E, however generally refers to fires involving electricity, therefore a bracketed E, "(E)" denoted on various types of extinguishers.

Fires are sometimes categorized as "one alarm", "two alarm", "three alarm" (or higher) fires. There is no standard definition for what this means quantifiably, though it always refers to the level response by the local authorities. In some cities, the numeric rating refers to the number of fire stations that have been summoned to the fire. In others, the number counts the number of "dispatches" for additional personnel and equipment.

COMPONENTS OF FIRE PROTECTION:
Structural fire protection (in land-based buildings, offshore construction or onboard ships) is typically achieved via three means:

Passive fire protection (use of integral, fire-resistance rated wall and floor assemblies that are used to form fire compartments intended to limit the spread of fire, or occupancy separations, or firewalls, to keep fires, high temperatures and flue gases within the fire compartment of origin, thus enabling firefighting and evacuation)

Active fire protection (manual and automatic detection and suppression of fires, as in using and installing a Fire Sprinkler system or finding the fire (Fire alarm) and/or extinguishing it)
Education (ensuring that building owners and operators have copies and a working understanding of the applicable building and fire codes, having a purpose-designed fire safety plan and ensuring that building occupants, operators and emergency personnel know the building, its means of Active fire protection and Passive fire protection, its weak spots and strengths to ensure the highest possible level of safety)

BUILDING OPERATION IN CONFORMANCE WITH FIRE PROTECTION DESIGN:
The building is designed in compliance with the local building code and fire code by the architect and other consultants. A building permit is issued after review by the Authority Having Jurisdiction (AHJ).

Deviations from that original plan should be made known to the AHJ to make sure that the change is still in compliance with the law to prevent any unsafe conditions that may violate the law and put people at risk. For example, if the fire stop systems in a structure were inoperable, a significant part of the fire safety plan would not work in the event of a fire because the walls and floors that contain the fire stops are intended to have a fire-resistance rating, which has been achieved through passing a fire test and, often, product certification of the components involved in the construction of those walls and floors.

Likewise, if the sprinkler system or fire alarm system is inoperable for lack of knowledgeable maintenance, or if the building occupants prop open a fire door and then run a carpet through, the likelihood of damage and casualties is increased. It is vital for everyone to realise that fire protection within a structure is a system that relies on all of its components.


[1] Fire Protection; From: http://en.wikipedia.org/wiki/Fire_protection (Retrieved May 3, 2011)

Saturday, April 30, 2011

WATER STORAGE AND DISTRIBUTION SYSTEMS IN BUILDINGS

AR-461: BUILDING SCIENCE
By:
RAVINDAR KUMAR
Assistant Professor
Department of Architecture and Planning
NED University of Engineering and Technology
Karachi
LECTURE NO. 26

TOPIC: 
WATER STORAGE AND DISTRIBUTION SYSTEMS IN BUILDINGS
HOT & COLD WATER SUPPLY / UNDERGROUND AND OVERHEAD TANKS / PIPE SIZING


INTRODUCTION:[1]
Vastu Shastra recommends some principles for construction of water sump in the building. According to Vastu, water elements should be available in the Northeast of the building. The following are some principles to build overhead and under ground water tanks.

UNDER GROUND WATER TANK/WATER SUMP:
The best place for digging the sump is the North-east of the plot. This leads to increase in wealth, prosperity and knowledge. While digging the sump, an axis should be drawn from the Northeast corner to southwest corner. The sump should be dug to the right or left side of axis. The sump in east of northeast is most beneficial and the sump in north of northeast is also good. Water sump should not be towards Southeast or Northwest. The sump in the Southwest is worst. Avoid water sump at the center of the house.
OVERHEAD WATER TANK:
Overhead water tank should be in the West or Southwest direction of the building as these are negative zones of the house. Due to water in the tank, it becomes heavy, creates a balance of energies in the house and proves to be useful. Overhead tank in west direction is also beneficial.   

Overhead tank should not be built in the Northeast of building.  The tank in northeast direction will make it heavy; which is a big Vastu defect. It should not also be built in the South-east as it may cause loss of wealth and has adverse effect on health. Tank can be built in the Northwest of the house, but it should be small in size. Overhead water tank is not good at center of house as it is a heavy structure and will make the center heavy. Tank should be 2 feet above form the slab. There should not be leakage in overhead tank as it can cause outflow of money. Overhead tank should not be made of plastic. If it is of plastic, it should be of black or blue color as these colors absorb sun rays which create positive energy when absorbed in water.

Note: All above principles are applicable to residential as well as commercial buildings.
WATER TANKS:[1]
Water tanks are liquid storage containers, these tanks are usually storing water for human consumption. The need for water tank systems is as old as civilized man. A water tank provides for the storage of drinking water, irrigation agriculture, fire suppression, agricultural farming and livestock, chemical manufacturing, food preparation as well as many other possible solutions.
Various materials are used for making a water tank: plastics (polyethylene, polypropylene), fiberglass, concrete, stone, steel (welded or bolted, carbon or stainless). Earthen ponds function as water storage and are often referred to as tanks.

MATERIALS USED IN THE MANUFACTURE OF WATER TANKS:

Ground water tank is made of lined carbon steel, it may receive water from water well or from surface water allowing a large volume of water to be placed in inventory and used during peak demand cycles.

Elevated Water Tanks also known as water towers, create a pressure at the ground-level tank outlet of 1 psi per 2.31 feet of elevation, thus a tank elevated to 70 feet creates about 30 psi of discharge pressure. 30 psi is sufficient for most domestic and industrial requirements.

Water tank application parameters include the general design of the tank, its materials of construction, as well as the following.

1.         Location of the water tank (indoors, outdoors, above ground or underground)
2.         Volume of water tank will need to hold
3.         What the water will be used for.
4.         Temperature of area where water will be stored, concern for freezing.
5.         Pressure requirements, domestic pressures range from 35-60 PSI
6.         How is the water to be delivered into and extracted, pumped out of the water tank?
7.         Wind and Earthquake design considerations allow water tanks to survive seismic and high wind events.
8.         Back flow prevention
9.         Chemical injection for bacteria and virus control

Throughout history, wood, ceramic and stone have been used as water tanks. These were all naturally occurring and manmade and some tanks are still in service.

The Indus Valley Civilization (3000–1500 BC) made use of granaries and water tanks. Medieval castles needed water tanks for the defenders to withstand a siege. A wooden water tank found at California was restored to functionality after being found completely overgrown with ivy. It had been built in 1884.

Vertical cylindrical dome top tanks may hold from fifty gallons to several million gallons. Horizontal cylindrical tanks are typically used for transport; this low-profile transport storage creates a low center of gravity helping to maintain equilibrium for the transport vehicle, trailer or truck.

Hydro-pneumatic tanks are typically horizontal pressurized storage tanks. Pressurizing this reservoir of water creates a surge free delivery of stored water into the distribution system.
There are many custom configurations that include various rectangular cube shaped tanks, cone bottom and special shapes for specific design requirements. By design a water tank/container should do no harm to the water. Water is susceptible to a number of ambient negative influences, including bacteria, viruses, algae, changes in pH, and accumulation of minerals. Correctly designed water tank systems work to mitigate these negative effects.

COPPER POISONING:
A falsely based news article, linked copper poisoning to plastic tanks, the article indicated that rainwater was collected and stored in plastic tanks and that the tank did nothing to mitigate the low Ph. The water was then brought into homes with copper piping; the copper was released by the high acid rainwater and caused poisoning in humans. It is important to note that while the plastic tank is an inert container, the collected acid rain could and should be analyzed, and ph adjusted before being brought into a domestic water supply system.

There is no "linkage" between the plastic tank and copper poisoning, a solution to the problem is easy, monitor 'stored rainwater' with 'swimming pool strips' cheap and available at, swimming pool supply outlets. If the water is too acidic, contact state/county/local health officials to obtain advice and precise solutions and ph limits and guidelines as to what should be used to treat rainwater to be used as domestic drinking water.

Tank Volume in US Gallons Volumes of simple tank geometry may be calculated as follows:

Beginning with the fact that a cubic foot contains 7.48 gallons;
A cube or rectangle is calculated at:
(Length) times (Width) times (Height) = (Cubic Feet) times (7.48) = gallons.
For a cylinder volume is calculated at:
Pi (3.14) times (radius squared) times (height) = (cubic feet) times (7.48) = gallons.

Articles and specifications for Water Tank applications and design considerations:
American Water Works Association the AWWA is a reservoir of water tank knowledge; the association provides specifications for a variety of water storage tank applications as well as design. The AWWA's site provides scientific resources with which the reader will be able to develop an informed perspective on which to make decisions regarding their water tank requirements. Architecture Dampening of high-rise building movement by using a highly placed volume water tank, the volume of water creates an inertia movement opposite to the building movement, slowing the building's movement, sway.

EQUIPMENT AND MATERIAL PRESSURE REQUIREMENTS:
The domestic water system must be designed to handle the high operating pressures at the base of the system. In this project, the required pressure at the discharge from the booster pumps is required to be 240 psi (1,655 kPa). Therefore, in addition to the booster pumps, the equipment, piping, valves, fittings, and pipe joints also must be designed, specified, and rated to accommodate the high water pressures at the base of the domestic water piping system. Components with a minimum 250-psi (1,725-kPa) rated operating pres- sure are required.
The related internal operating pressure for copper tubing also must be considered in systems with high operating pressures, and the limitation is based on the type of alloy used for the joints. Lead as occurs in 50-50 tin-lead solder never should be used in making joints on potable water systems, regard- less of the pressure. For example, tin-antimony 95-5 solder has a maximum operating pressure of only 180 psi (1,240 kPa) at 200°F (93°C) for a 6-inch (150-millimeter) pipe diameter joint. Brazing alloys and silver solder have significantly higher operating pressure limits and should be specified for small-diameter copper tubing, while grooved-end mechanical joint systems may be considered for 2-in. (50-mm) diameter and larger copper tubing.

Note that for taller buildings, water pressure requirements at the base of the system are increasingly higher, unless mechanical rooms are provided at intermediate levels within the building and pumping can be staged in series. At levels further up the building, the pressures are correspondingly lower, and equipment and materials can be designed to lower pressure ratings.

DOMESTIC WATER PRESSURE BOOSTER PUMPS:
Several domestic water pressure booster pump arrangements were evaluated. The first consideration was to reduce the pumping energy generally associated with booster pump systems. Two factors can contribute significantly to wasted energy. First are systems that incorporate one pump to run continuously, even during low-flow or no-flow periods, and utilize a thermal bleed solenoid valve to dump water that is overheated in the pump casing due to the impeller operating below the demand flow rate. This wastes both energy and water. Second are systems that generate a single water pres- sure for the entire building that is high enough to satisfy the upper-level fixtures and then reduce that pressure through pressure-reducing valves to satisfy lower-level pressure zones in the building.

The initial design approach for the project was to provide separate booster pumps for each pressure zone in the building with each pump incorporating a variable-speed drive. This would eliminate both of the energy-wasting aspects described above. Each of the five pressure zone booster systems would consist of a simplex pump, with just one additional backup pump that would be interconnected with normally closed valves to all of the zone headers, thus providing backup for each of the zones when one of the simplex pumps was being serviced. The total connected pump horsepower for the project and the total energy consumption were lowest in this scenario. In addition, this arrangement did not require any pressure-reducing stations at the upper floors of the building, thereby increasing valuable floor area and reducing associated adjustments or maintenance work at the public floor levels. However, this scenario required additional risers, one cold water riser and one hot water riser, for each pres- sure zone in the building, running from the basement-level mechanical room up to the level of each zone. This scenario was presented as the primary system for costing.

The second scenario that was evaluated consisted of one triplex booster package for the cold water system and a separate triplex booster package for the hot water system, with pressure-reducing valve (PRV) stations for each pressure zone, located in valve closets at intermittent floor levels in the building. The domestic water heaters were located in the basement mechanical room on the upstream side of the hot water system pressure booster pumps with their cold water supply at city water pressure.

The third scenario consisted of one triplex booster pump package for the cold and hot water systems, with PRV stations located in valve closets at each pressure zone in the building. To minimize the size of the PRV station closets, the valve stations were staggered, with cold water PRVs on one level, hot water PRVs on a second level, hot water zone circulating pumps on a third level, and hot water zone electric reheat tanks on a fourth level. This pumping scenario required the primary domestic water heaters to be ASME rated for 250-psi (1,725-kPa) operation, as they were located in the basement mechanical room on the downstream side of the booster pumps. However, the lower number of booster pumps and associated interconnecting piping offset the premium cost for the higher pressure rating of the water heaters.

The offsetting increase in capital cost is the increased number of risers and total length of riser piping and insulation, plus the interconnecting piping and valves to each of the pumps and the associated installation costs. On building projects where the client will be paying both the capital and long-term operating costs, the payback period may be worth- while. Unfortunately, in the developer’s world where capital cost is king and operating costs are paid by a multitude of unknown owners in the future, payback periods are generally not marketable or sufficient to support these creative engineering solutions.

DOMESTIC WATER PIPE DISTRIBUTION WITHIN THE SUITES:
Traditionally in Vancouver, water distribution piping has been Type L copper tube manufactured to ASTM B 88 standards, with wrought copper fittings and 95-5 soldered joints. Distribution piping has been routed within drop ceiling spaces and down within partition walls to the plumbing fixtures. The recent rise in the cost of copper materials and the labor cost of installation necessitated a trend to a different solution.

Over the past several years, cross-linked polyethylene (PEX) tubing has been used extensively. The material has several advantages, including lower material capital cost, lower installation cost, less joints and therefore less potential locations for leaks in concealed spaces, faster installation, and no potential for corrosion by aggressive local municipal water conditions, which has contributed to pinhole damage and expensive replacement of entire copper potable water systems in high-rise buildings.

The common installation within a suite consists of brass isolation ball valves on the cold and hot water supplies generally located in a closet wall, short¾-in. (19-mm) or 1-in. (25-mm) diameter headers with several½- in. (12-mm) connections, and individual runs of PEX tubing from the headers to each plumbing fixture. The PEX tubing is routed within the structural floor slabs, and one major PEX tubing supplier has obtained a tested third-party listing for a two-hour fire separation rating. Quarter-turn mini ball valves are provided at each plumbing fixture, and water hammer arrestors are provided at dishwashers and clothes washers.

SUMMARY:
Many variables must be considered during the engineering of domestic water systems for high-rise buildings, and many design solutions are available to the plumbing engineer. The water pressures vary at each level throughout the building and always must be considered in system layouts and when selecting equipment and pipe materials. Energy efficiency, space allocations, economics, and acoustics all play important roles in a successful project delivery to the client.
TAP WATER:[2]
Tap water, running water, city water, municipal water, etc. is a principal component of "indoor plumbing", which became available in urban areas of the developed world during the last quarter of the 19th century, and common during the mid-20th century. The application of technologies involved in providing clean or "potable" water to homes, businesses and public buildings is a major subfield of sanitary engineering.

The availability of tap water has major public health benefits, since it typically vastly reduces the risk to the public of contracting water-borne diseases. Providing tap water to large urban or suburban populations requires a complex and carefully designed system of collection, storage, treatment and distribution, and is commonly the responsibility of a government agency, often the same agency responsible for the removal and treatment of wastewater.

Specific chemical compounds are often added to tap water during the treatment process to adjust the pH or remove contaminants, as well as chlorine to kill biological toxins. Local geological conditions affecting groundwater are determining factors for the presence of various metal ions, often rendering the water "soft" or "hard".

Tap water remains susceptible to biological or chemical contamination. In the event of contamination deemed dangerous to public health, government officials typically issue an advisory regarding water consumption. In the case of biological contamination, residents are usually advised to boil their water before consumption or to use bottled water as an alternative. In the case of chemical contamination, residents may be advised to refrain from consuming tap water entirely until the matter is resolved.

In many areas a compound of fluoride is added to tap water in an effort to improve dental health among the public. In some communities "fluoridation" remains a controversial issue.

POTABLE WATER SUPPLY:
This supply may come from several possible sources.

  1. Municipal water supply
  2. Water wells
  3. Delivered by truck
  4. Processed water from creeks, streams, rivers, lakes, rainwater, etc.

Domestic water systems have been evolving since people first located their homes near a running water supply, e.g., a stream or river. The water flow also allowed sending waste water away from the domiciles.

Modern indoor plumbing delivers clean, safe, potable water to each service point in the distribution system. It is imperative that the clean water not be contaminated by the waste water (disposal) side of the process system. Historically, this contamination of drinking water has been the largest killer of humans.

HOT WATER SUPPLY:
Domestic hot water is provided by means of water heater appliances, or through district heating. The hot water from these units is then piped to the various fixtures and appliances that require hot water, such as lavatories, sinks, bathtubs, showers, washing machines, and dishwashers.

FIXTURES AND APPLIANCES:
Everything in a building that uses water falls under one of two categories; Fixture or Appliance. As the consumption points above perform their function, most produce waste/sewage components that will require removal by the waste/sewage side of the system. The minimum is an air gap.
Cross connection control & backflow prevention for an overview of backflow prevention methods and devices currently in use, both through the use of mechanical and physical principles. Fixtures are devices that use water without an additional source of power.

PIPE MATERIALS:
In old construction, lead plumbing was common. It was generally eclipsed toward the end of the 1800s by galvanized iron water pipes which were attached with threaded pipe fittings. Higher durability, and cost, systems were made with brass pipe and fittings. Copper with soldered fittings became popular around 1950, though it had been used as early as 1900. Plastic supply pipes have become increasingly common since about 1970, with a variety of materials and fittings employed, however plastic water pipes do not keep water as clean as copper and brass piping does. Copper pipe plumbing is bacteriostatic. This means that bacteria can't grow in the copper pipes. Plumbing codes define which materials may be used, and all materials must be proven by ASTM, UL, and/or NFPA testing.

STEEL:
Galvanized steel potable water supply and distribution pipes are commonly found with nominal diameters from 3/8" to 2". It is rarely used today for new construction residential plumbing. Steel pipe has National Pipe Thread (NPT) standard tapered male threads, which connect with female tapered threads on elbows, tees, couplers, valves, and other fittings. Galvanized steel (often known simply as "galv" or "iron" in the plumbing trade) is relatively expensive, difficult to work with due to weight and requirement of a pipe threader. It remains in common use for repair of existing "galv" systems and to satisfy building code non-combustibility requirements typically found in hotels, apartment buildings and other commercial applications. It is also extremely durable. Black lacquered steel pipe is the most widely used pipe material for fire sprinklers and natural gas. Most single family homes' systems typically won't require supply piping larger than 3/4". In addition to expense, another downside is it suffers from a tendency to obstruction due to internal rusting and mineral deposits forming on the inside of the pipe over time after the internal galvanizing zinc coating has degraded. In potable water distribution service, galvanized steel pipe has a service life of about 30 to 50 years, although it is not uncommon for it to be less in geographic areas with corrosive water contaminants.

COPPER:
Tubing made of copper was introduced in about 1900, but didn't become popular until approximately 1950, depending on local building code adoption.

Sizes:
Common wall-thicknesses of copper tubing in the USA are "Type K", "Type L" and "Type M":

Type K has the thickest wall section of the three types of pressure rated tubing and is commonly used for deep underground burial such as under sidewalks and streets, with a suitable corrosion protection coating or continuous polyethylene sleeve as required by code.
Type L has a thinner pipe wall section, and is used in residential and commercial water supply and pressure applications.

Type M has the thinnest wall section, and is generally suitable for condensate and other drains, but sometimes illegal for pressure applications, depending on local codes.

Types K and L are generally available in both hard drawn "sticks" and in rolls of soft annealed tubing, whereas type M is usually only available in hard drawn "sticks".

In the plumbing trade the size of copper tubing is measured by its nominal diameter (average inside diameter). Some American trades, heating and cooling technicians for instance, use the outside diameter (OD) to designate copper tube sizes. The HVAC tradesman also use this different measurement to try and not confuse water pipe with copper pipe used for the HVAC trade, as pipe used in the air-conditioning trade uses copper pipe that is made at the factory without processing oils that would be incompatible with the oils used to lubricate the compressors in the AC system. The OD of copper tube is 1⁄8th inch larger than its nominal size. Therefore, 1 inch nominal copper tube and 1 1⁄8th inch ACR tube are exactly the same tube with different size designations. The wall thickness of the tube, as mentioned above, never affects the sizing of the tube. Type K 1⁄2 inch nominal tube, is the same size as Type L 1⁄2 inch nominal tube (5⁄8 inch ACR).

Common wall-thicknesses in Europe are "Type X", "Type Y" and "Type Z", defined by the EN 1057 standard.

Type X is the most common, and is used in above ground services including drinking water supply, hot and cold water systems, sanitation, central heating and other general purpose applications.

Type Y is a thicker walled pipe, used for underground works and heavy duty requirements including hot and cold water supply, gas reticulation, sanitary plumbing, heating and general engineering.

Type Z is a thinner walled pipe, also used for above ground services including drinking water supply, hot and cold water systems, sanitation, central heating and other general purpose applications.

In the plumbing trade the size of copper tubing is measured by its outside diameter in millimeters. Common sizes are 15 mm and 22 mm.

Thin-walled types used to be relatively inexpensive, but since 2002 copper prices have risen considerably due to rising global demand and a stagnant supply.

LEAD LEACHING:
Generally, copper tubes are soldered directly into copper or brass fittings, although compression, crimp, or flare fittings are also used.
Formerly, concerns with copper supply tubes included the lead used in the solder at joints (50% tin and 50% lead). Some studies have shown significant "leaching" of the lead into the potable water stream, particularly after long periods of low usage, followed by peak demand periods. In hard water applications, shortly after installation, the interior of the pipes will be coated with the deposited minerals that had been dissolved in the water, and therefore the vast majority of exposed lead is prevented from entering the potable water. Building codes now require lead-free solder. Building Codes throughout the U.S. require the use of virtually "lead-free" (<.2% lead) solder or filler metals in plumbing fittings and appliances as well.

CORROSION:
Copper water tubes are susceptible to: cold water pitting caused by contamination of the pipe interior typically with soldering flux; erosion corrosion caused by high speed or turbulent flow; and stray current corrosion, caused by poor electrical wiring technique, such as improper grounding and bonding.

PIN HOLES DUE TO POOR PLUMBING ELECTRICAL GROUNDING AND/OR BONDING:
Pin-hole leaks can occur anytime copper piping is improperly grounded and/or bonded; nonmetal piping, such as Pex or PVC, does not suffer from this problem. The phenomenon is known technically as stray current corrosion or electrolytic pitting. Pin-holing due to poor grounding or poor bonding occurs typically in homes where the original plumbing has been modified; homeowners may find a new plastic water filtration device or plastic repair union has interrupted the water pipe's electrical continuity to ground when they start seeing pinhole water leaks after a recent install. Damage occurs rapidly, usually being seen about six months after the ground interruption. Correctly installed plumbing appliances will have a copper bonding jumper cable connecting the interrupted pipe sections. Pinhole leaks from stray current corrosion can result in thousands of dollars in plumbing bills, and sometimes necessitating the replacement of the entire affected line. The cause is an electrical problem, not a plumbing problem; once the plumbing damage is repaired, an electrician should be consulted to evaluate the grounding and bonding of the entire plumbing system. The difference between a ground and a bond is subtle.

STRAY CURRENT CORROSION OCCURS BECAUSE:
  1. The piping system is connected accidentally or intentionally to a DC voltage source;
  2. The piping does not have metal-to-metal electrical continuity;
  3. If the voltage source is AC, one or more naturally occurring minerals coating the pipe interior act as a rectifier, converting AC current to DC.

The DC voltage forces the water within the piping to act as an electrical conductor (an electrolyte). Electric current leaves the copper pipe, moves though the water across the nonconductive section (the plastic filter housing in the example above), and reenters the pipe on the opposite side. Pitting occurs at the electrically negative side (the cathode), which may be upstream or downstream with respect to the water flow direction. Pitting occurs because the electrical voltage ionizes the pipe's interior copper metal, which reacts chemically with dissolved minerals in the water creating copper salts; these copper salts are soluble in water and wash away. Pits eventually grow and consolidate to form pin holes. Where there is one, there are almost certainly more. A complete discussion of stray current corrosion can be found in chapter 11, section 11.4.3, of Handbook of Corrosion Engineering, by Pierre Roberge.

Detecting and eliminating poor bonding is relatively straightforward. Detection is accomplished by use of a simple voltmeter set to DC with the leads placed in various places in the plumbing. Typically, a probe on a hot pipe and a probe on a cold pipe will tell you if there is improper grounding. Anything beyond a few millivolts is important; potentials of 200 mV are common. A missing bond will show up best in the area of the gap, as potential disperses as the water runs. Since the missing bond is usually seen near the water source, as filtration and treatment equipment are added, pinhole leaks can occur anywhere downstream. It is usually the cold water pipe, as this is the one that gets the treatment devices.

Correcting the problem is a simple matter of either purchasing a copper bonding jumper kit, composed of copper cable at least #6 AWG in diameter and two bronze ground clamps for affixing it the plumbing. See NFPA 7, the U.S. National Electrical Code Handbook (NEC), section on bonding and ground for details on selecting the correct bonding conductor wire size. A similar bonding jumper wire can also be seen crossing gas meters, but for a different reason.

Note if homeowners are experiencing shocks or sparks from plumbing fixtures or pipes, it is more than a missing bond; it is likely a live electrical wire is bridging to the plumbing and the plumbing system is not grounded. This is an electrical shock hazard and potential fire danger; consult an electrician immediately!

PLASTICS:
Plastic pipe is in wide use for domestic water supply and drainage, waste, and vent (DWV) pipe. For example, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polypropylene (PP), polybutylene (PB), and polyethylene (PE) may be allowed by code for certain uses. Some examples of plastics in water supply systems are:

PVC/CPVC - rigid plastic pipes similar to PVC drain pipes but with thicker walls to deal with municipal water pressure, introduced around 1970. PVC should be used for cold water only, or venting. CPVC can be used for hot and cold potable water supply. Connections are made with primers and solvent cements as required by code.

PP - The material is used primarily in house wares, food packaging, and clinical equipment,[5] but since the early 1970s has seen increasing use worldwide for both domestic hot and cold water. PP pipes are heat fused, preventing the use of glues, solvents, or mechanical fittings. PP pipe is often used in green building projects.[6][7]

PBT - flexible (usually gray or black) plastic pipe which is attached to barbed fittings and secured in place with a copper crimp ring; The primary manufacturer of PBT tubing and fittings was driven into bankruptcy by a class-action lawsuit over failures of this system. However, PB and PBT tubing has returned to the market and codes, typically first for 'exposed locations' such as risers.

PEX - cross linked polyethylene system with mechanically joined fittings employing barbs and crimped steel or copper fittings.
Polytanks - plastic polyethylene cisterns, underground water tanks, above ground water tanks, are made of linear polyethylene suitable as a potable water storage tank, provided in white, black or green, approved by NSF and made of FDA approved materials.
Aqua - known as PEX-Al-PEX, for its PEX/aluminum sandwich - aluminum pipe sandwiched between layers of PEX and connected with brass compression fittings. In 2005, a large number of their fittings were recalled.

FITTINGS AND VALVES:
Potable water supply systems require not only pipe, but also many fittings and valves which add considerably to their functionality as well as cost. The Piping and plumbing fittings and Valves articles discuss them further.

REGULATION AND COMPLIANCE:
Before a water supply system is constructed or modified, the designer and contractor need to consult the local plumbing code and obtain a building permit prior to construction. Even replacing an existing water heater may require a permit and inspection of the work. NSF 61 is the U.S. national standard for potable water piping guidelines. National and local fire codes should be integrated in the design phase of the water system too to prevent "failures comply with regulations" notices. Some areas of the United States require on-site water reserves of potable and fire water by law.

WASTE WATER:
The waste water from the various appliances, fixtures, and taps is transferred to the waste and sewage removal system via the sewage drain system. This system consists of larger diameter piping, water traps, and is well vented to prevent toxic gases from entering the living space. The plumbing drains and vents article discusses the topic further, and introduces sewage treatment.

FOR FURTHER DETAILS PLEASE DO VISIT THE FOLLWING WEBSITES / REFERENCES:


[1] Water Tank; From: http://en.wikipedia.org/wiki/Water_tank (Retrieved May 2, 2011)
[2] Tap Water; From: http://en.wikipedia.org/wiki/Domestic_water_system (Retrieved May 2, 2011)
[3] Underground and Overhead Water Tank; From: http://www.gharexpert.com/articles/Vastu-Shastra-1725/Vastu-Water-Tank_0.aspx (Retrieved April 30, 2011)
[4] Domestic Water System; From: http://en.wikipedia.org/wiki/Domestic_water_system (Retrieved May 2, 2011)
[5]  Water Purification; From: http://en.wikipedia.org/wiki/Water_purification (Retrieved May 2, 2011)
[6]  Water Well; From: http://en.wikipedia.org/wiki/Water_well (Retrieved May 2, 2011)
[7] Water Supply System; From: http://www.engineeringtoolbox.com/water-supply-systems-d_477.html (Retrieved May 2, 2011)
[8] High Rise Structures, Plumbing Design Guidelines; From: http://www.scribd.com/doc/12632370/High-Rise-StructuresPlumbing-Design-Guidelines (Retrieved May 2, 2011)