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:

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[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)