Saturday, April 30, 2011


Assistant Professor
Department of Architecture and Planning
NED University of Engineering and Technology


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.

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 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 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.


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.

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.

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.

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.

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.

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, 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.

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.

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.

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.

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.

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.

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

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.

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.

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-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.

  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!

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.

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.

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.

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.


[1] Water Tank; From: (Retrieved May 2, 2011)
[2] Tap Water; From: (Retrieved May 2, 2011)
[3] Underground and Overhead Water Tank; From: (Retrieved April 30, 2011)
[4] Domestic Water System; From: (Retrieved May 2, 2011)
[5]  Water Purification; From: (Retrieved May 2, 2011)
[6]  Water Well; From: (Retrieved May 2, 2011)
[7] Water Supply System; From: (Retrieved May 2, 2011)
[8] High Rise Structures, Plumbing Design Guidelines; From: (Retrieved May 2, 2011)


Assistant Professor
Department of Architecture and Planning
NED University of Engineering and Technology
TOPIC:                                     WATER SUPPLY AND DRAINAGE

Water supply[1] is the provision by public utilities, commercial organisations, community endeavours or by individuals of water, usually by a system of pumps and pipes. Irrigation is covered separately. Drainage[2] is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.

In 2010 about 84% of the global population (6.74 billion people) had access to piped water supply through house connections or to an improved water source through other means than house, including standpipes, "water kiosks", protected springs and protected wells. However, about 14% (884 million people) did not have access to an improved water source and had to use unprotected wells or springs, canals, lakes or rivers for their water needs. A clean water supply, especially so with regard to sewage, is the single most important determinant of public health. Destruction of water supply and/or sewage disposal infrastructure after major catastrophes (earthquakes, floods, war, etc.) poses the immediate threat of severe epidemics of waterborne diseases, several of which can be life-threatening.

Water supply systems get water from a variety of locations, including groundwater (aquifers), surface water (lakes and rivers), conservation and the sea through desalination. The water is then, in most cases, purified, disinfected through chlorination and sometimes fluoridated. Treated water then either flows by gravity or is pumped to reservoirs, which can be elevated such as water towers or on the ground (for indicators related to the efficiency of drinking water distribution see non-revenue water). Once water is used, wastewater is typically discharged in a sewer system and treated in a wastewater treatment plant before being discharged into a river, lake or the sea or reused for landscaping, irrigation or industrial use.

Many of the 3.5 billion people having access to piped water receive a poor or very poor quality of service, especially in developing countries where about 80% of the world population lives. Water supply service quality has many dimensions: continuity; water quality; pressure; and the degree of responsiveness of service providers to customer complaints.

Continuity of water supply is taken for granted in most developed countries, but is a severe problem in many developing countries, where sometimes water is only provided for a few hours every day or a few days a week. It is estimated that about half of the population of developing countries receives water on an intermittent basis.

Drinking water quality has a micro-biological and a physico-chemical dimension. There are thousands of parameters of water quality. In public water supply systems water should, at a minimum, be disinfected — most commonly through the use of chlorination or the use of ultra violet light — or it may need to undergo treatment, especially in the case of surface water. For more details please see the separate entries on water quality, water treatment and drinking water.

Water pressures vary in different locations of a distribution system. Water mains below the street may operate at higher pressures, with a pressure reducer located at each point where the water enters a building or a house. In poorly managed systems, water pressure can be so low as to result only in a trickle of water or so high that it leads to damage to plumbing fixtures and waste of water. Pressure in an urban water system is typically maintained either by a pressurized water tank serving an urban area, by pumping the water up into a tower and relying on gravity to maintain a constant pressure in the system or solely by pumps at the water treatment plant and repeater pumping stations.

Typical UK pressures are 4-5 bar for an urban supply. However, some people can get over 8 bars or below one bar. A single iron main pipe may cross a deep valley, it will have the same nominal pressure; however each consumer will get a bit more or less because of the hydrostatic pressure (about 1 bar/10m height). So people at the bottom of a 100-foot (30 m) hill will get about 3 bars more than those at the top.

The effective pressure also varies because of the supply resistance even for the same static pressure. An urban consumer may have 5 meters of 1/2" lead pipe running from the iron main, so the kitchen tap flow will be fairly unrestricted, so high flow. A rural consumer may have a kilometer of rusted and limed 3/4" iron pipe so their kitchen tap flow will be small.

For this reason the UK domestic water system has traditionally (prior to 1989) employed a "cistern feed" system, where the incoming supply is connected to the kitchen sink and also a header/storage tank in the attic. Water can dribble into this tank through a 1/2" lead pipe, plus ball valve, and then supply the house on 22 or 28 mm pipes. Gravity water has a small pressure (say 1/4 bar in the bathroom) but needs wide pipes allow higher flows. This is fine for baths and toilets but is frequently inadequate for showers. People install shower booster pumps to increase the pressure. For this reason urban houses are increasingly using mains pressure boilers which take a long time to fill a bath but suit the high back pressure of a shower.

Comparing the performance of water and sanitation service providers (utilities) is needed, because the sector offers limited scope for direct competition (natural monopoly). Firms operating in competitive markets are under constant pressure to out perform each other.
Water utilities are often sheltered from this pressure, and it frequently shows: some utilities are on a sustained improvement track, but many others keep falling further behind best practice. Benchmarking the performance of utilities allows to simulate; competition, establish realistic targets for improvement and create pressure to catch up with better utilities. Information on benchmarks for water and sanitation utilities is provided by the International Benchmarking Network for Water and Sanitation Utilities.

A great variety of institutions have responsibilities in water supply. A basic distinction is between institutions responsible for policy and regulation on the one hand; and institutions in charge of providing services on the other hand. Water supply policies and regulation are usually defined by one or several Ministries, in consultation with the legislative branch. Dozens of countries around the world have established regulatory agencies for infrastructure services, including often water supply and sanitation, in order to better protect consumers and to improve efficiency.

Regulatory agencies can be entrusted with a variety of responsibilities, including in particular the approval of tariff increases and the management of sector information systems, including benchmarking systems. Sometimes they also have a mandate to settle complaints by consumers that have not been dealt with satisfactorily by service providers. These specialized entities are expected to be more competent and objective in regulating service providers than departments of government Ministries. Regulatory agencies are supposed to be autonomous from the executive branch of government, but in many countries have often not been able to exercise a great degree of autonomy.

Many countries do not have regulatory agencies for water. In these countries service providers are regulated directly by local government, or the national government. This is, for example, the case in the countries of continental Europe, in China and India.

An estimated 10 percent of urban water supply is provided by private or mixed public-private companies, usually under concessions, leases or management contracts. Under these arrangements the public entity that is legally responsible for service provision delegates certain or all aspects of service provision to the private service provider for a period typically ranging from 4 to 30 years. The public entity continues to own the assets. These arrangements are common in France and in Spain. Only in few parts of the world water supply systems have been completely sold to the private sector (privatization), such as in England and Wales as well as in Chile.

90% of urban water supply and sanitation services are currently in the public sector. They are owned by the state or local authorities, or also by collectives or cooperatives. They run without an aim for profit but are based on the ethos of providing a common good considered to be of public interest. In most middle and low-income countries, these publicly-owned and managed water providers can be inefficient as a result of political interference, leading to over-staffing and low labour productivity. Ironically, the main losers from this institutional arrangement are the urban poor in these countries. Because they are not connected to the network, they end up paying far more per litre of water than do more well-off households connected to the network who benefit from the implicit subsidies that they receive from loss-making utilities.
We are still so far from achieving universal access to clean water and sanitation shows that public water authorities, in their current state, are not working well enough. Yet some are being very successful and are modelling the best forms of public management. As Public water services currently provide more than 90 per cent of water supply in the world. Modest improvement in public water operators will have immense impact on global provision of services."

Governance arrangements for both public and private utilities can take many forms. Governance arrangements define the relationship between the service provider, its owners, its customers and regulatory entities. They determine the financial autonomy of the service provider and thus its ability to maintain its assets, expand services, attract and retain qualified staff, and ultimately to provide high-quality services. Key aspects of governance arrangements are the extent to which the entity in charge of providing services is insulated from arbitrary political intervention; and whether there is an explicit mandate and political will to allow the service provider to recover all or at least most of its costs through tariffs and retain these revenues. If water supply is the responsibility of a department that is integrated in the administration of a city, town or municipality, there is a risk that tariff revenues are diverted for other purposes. In some cases, there is also a risk that staff are appointed mainly on political grounds rather than based on their professional credentials.

Almost all service providers in the world charge tariffs to recover part of their costs. According to estimates by the World Bank the average (mean) global water tariff is US$ 0.53 per cubic meter. In developed countries the average tariff is US$ 1.04, while it is only U$ 0.11 in the poorest developing countries. The lowest tariffs in developing countries are found in South Asia (mean of US$ 0.09/m3), while the highest are found in Latin America (US$ 0.41/m3). Few utilities do recover all their costs. According to the same World Bank study only 30% of utilities globally, and only 50% of utilities in developed countries generate sufficient revenue to cover operation, maintenance and partial capital costs.

According to another study undertaken in 2006 by NUS Consulting, the average water and sewerage tariff in 14 mainly OECD countries excluding VAT varied between US$ 0.66 per cubic meter in the United States and the equivalent of US$ 2.25 per cubic meter in Denmark. However, water consumption is much higher in the US than in Europe. Therefore, residential water bills may be very similar, even if the tariff per unit of consumption tends to be higher in Europe than in the US. A typical family on the US East Coast paid between US$30 and US$70 per month for water and sewer services in 2005.

In developing countries tariffs are usually much further from covering costs. Residential water bills for a typical consumption of 15 cubic meters per month vary between less than US$ 1 and US$ 12 per month. Water and sanitation tariffs, which are almost always billed together, can take many different forms. Where meters are installed, tariffs are typically volumetric (per usage), sometimes combined with a small monthly fixed charge. In the absence of meters, flat or fixed rates which are independent of actual consumption are being charged. In developed countries, tariffs are usually the same for different categories of users and for different levels of consumption. In developing countries, are often characterized by cross-subsidies with the intent to make water more affordable for residential low-volume users that are assumed to be poor. For example, industrial and commercial users are often charged higher tariffs than public or residential users.
Also, metered users are often charged higher tariffs for higher levels of consumption (increasing-block tariffs). However, cross-subsidies between residential users do not always reach their objective. Given the overall low level of water tariffs in developing countries even at higher levels of consumption, most consumption subsidies benefit the wealthier segments of society. Also, high industrial and commercial tariffs can provide an incentive for these users to supply water from other sources than the utility (own wells, water tankers) and thus actually erode the utility's revenue base.

Metering of water supply is usually motivated by one or several of four objectives: First, it provides an incentive to conserve water which protects water resources (environmental objective). Second, it can postpone costly system expansion and saves energy and chemical costs (economic objective). Third, it allows a utility to better locate distribution losses (technical objective). Fourth, it allows to charge for, water based on use, which is perceived by many as the fairest way to allocate the costs of water supply to users. Metering is considered good practice in water supply and is widespread in developed countries, except for the United Kingdom. In developing countries it is estimated that half of all urban water supply systems are metered and the tendency is increasing.

Water meters are read by one of several methods:

  1. the water customer writes down the meter reading and mails in a postcard with this info to the water department;
  2. the water customer writes down the meter reading and uses a phone dial-in system to transfer this info to the water department;
  3. the water customer logs in to the website of the water supply company, enters the address, meter ID and meter readings
  4. a meter reader comes to the premise and enters the meter reading into a handheld computer;
  5. the meter reading is echoed on a display unit mounted to the outside of the premise, where a meter reader records them;
  6. a small radio is hooked up to the meter to automatically transmit readings to corresponding receivers in handheld computers, utility vehicles or distributed collectors
  7. a small computer is hooked up to the meter that can either dial out or receive automated phone calls that give the reading to a central computer system.
  8. Most cities are increasingly installing Automatic Meter Reading (AMR) systems to prevent fraud, to lower ever-increasing labor and liability costs and to improve customer service and satisfaction.

The cost of supplying water consists to a very large extent of fixed costs (capital costs and personnel costs) and only to a small extent of variable costs that depend on the amount of water consumed (mainly energy and chemicals). The full cost of supplying water in urban areas in developed countries is about US$1–2 per cubic meter depending on local costs and local water consumption levels. The cost of sanitation (sewerage and wastewater treatment) is another US$1–2 per cubic meter. These costs are somewhat lower in developing countries. Throughout the world, only part of these costs is usually billed to consumers, the remainder being financed through direct or indirect subsidies from local, regional or national governments.
Besides subsidies water supply investments are financed through internally generated revenues as well as through debt. Debt financing can take the form of credits from commercial Banks, credits from international financial institutions such as the World Bank and regional development banks (in the case of developing countries), and bonds (in the case of some developed countries and some upper middle-income countries).

A water supply system or water supply network is a system of engineered hydrologic and hydraulic components which provide water supply. A water supply system typically includes:

  1. A drainage basin (sources of drinking water);
  2. A raw (untreated) water collection point (above or below ground) where the water accumulates, such as a lake, a river, or groundwater from an underground aquifer. Untreated drinking water (usually water being transferred to the water purification facilities) may be transferred using uncovered ground-level aqueducts, covered tunnels or underground water pipes.
  3. Water purification facilities. Treated water is transferred using water pipes (usually underground).
  4. Water storage facilities such as reservoirs, water tanks, or water towers. Smaller water systems may store the water in cisterns or pressure vessels. (Tall buildings may also need to store water locally in pressure vessels in order for the water to reach the upper floors.)
  5. Additional water pressurizing components such as pumping stations may need to be situated at the outlet of underground or above ground reservoirs or cisterns (if gravity flow is impractical)
  6. A pipe network for distribution of water to the consumers (which may be private houses or industrial, commercial or institution establishments) and other usage points (such as fire hydrants)
  7. Connections to the sewers (underground pipes, or aboveground ditches in some developing countries) are generally found downstream of the water consumers, but the sewer system is considered to be a separate system, rather than part of the water supply system

The ancient Indus systems of sewerage and drainage that were developed and used in cities throughout the civilization were far more advanced than any found in contemporary urban sites in the Middle East and even more efficient than those in some areas of modern Pakistan and India today. All houses in the major cities of Harappa and Mohenjo-daro had access to water and drainage facilities. Waste water was directed to covered drains, which lined the major streets. This operation is always best performed in spring or summer, when the ground is dry. Main drains ought to be made in every part of the field where a cross-cut or open drain was formerly wanted; they ought to be cut four feet (1.2 m) deep, upon an average. This completely secures them from the possibility of being damaged by the treading of horses or cattle, and being so far below the small drains, clears the water finely out of them. In every situation, pipe-turfs for the main drains, if they can be had, are preferable. Good stiff clay, a single row of pipe-turf; if sandy, a double row.
When pipe-turf cannot be got conveniently, a good wedge drain may answer well, when the subsoil is a strong, stiff clay; but if the subsoil be only moderately so, a thorn drain, with couples below, will do still better; and if the subsoil is very sandy, except pipes can be had, it is in vain to attempt under-draining the field by any other method. It may be necessary to mention here that the size of the main drains ought to be regulated according to the length and declivity of the run, and t either it can be he quantity of water to be carried off by them. It is always safe, however, to have the main drains large and plenty of them; for economy here seldom turns out well. Having finished the main drains, precede next to make a small drain in every furrow of the field if the ridges formerly have not been less than fifteen feet (4.6 m) wide. But if that should be the case, first level the ridges, and make the drains in the best direction, and at such a distance from each other as may be thought necessary.

If the water rises well in the bottom of the drains, they ought to be cut three feet (1 m) deep, and in this ease would dry the field sufficiently well, although they were from twenty-five to thirty feet (8 to 10 m) asunder; but if the water does not draw well to the bottom of the drains, two feet (0.6 m) will be a sufficient deepness for the pipe-drain, and two and a half feet (1 m) for the wedge drain. In no case ought they to be shallower where the field has been previously leveled. In this instance, however, as the surface water is carried off chiefly by the water sinking immediately into the top of the drains, it will be necessary to have the drains much nearer each other—say from fifteen to twenty feet (4.6 to 6 m). If the ridges are more than fifteen feet (4.6 m) wide, however broad and irregular they may be, follow invariably the line of the old furrows, as the best direction for the drains; and, where they are high-gathered ridges, from twenty to twenty-four inches will be a sufficient depth for the pipe-drain, and from twenty-four to thirty inches for the wedge-drain. Particular care should be taken in connecting the small and main drains together, so that the water may have a gentle declivity, with free access into the main drains.

When the drains are finished, the ridges are cleaved down upon the drains by the plough; and where they had been very high formerly, a second clearing may be given; but it is better not to level the ridges too much, for by allowing them to retain a little of their former shape, the ground being lowest immediately where the drains are, the surface water collects upon the top of the drains; and, by shrinking into them, gets freely away. After the field is thus finished, run the new ridges across the small drains, making them about ten feet (3 m) broad, and continue afterwards to plough the field in the same manner as dry land.

It is evident from the above method of draining that the expense will vary very much, according to the quantity of main drains necessary for the field, the distance of the small drains from each other, and the distance the turf is to be carried. The advantage resulting from under-draining, is very great, for besides a considerable saving annually of water furrowing, cross cutting, etc., the land can often be ploughed and sown to advantage, both in the spring and in the fall of the year, when otherwise it would be found quite impracticable; every species of drilled crops, such as beans, potatoes, turnips, etc., can be cultivated successfully; and every species, both of green and white crops, is less apt to fail in wet and untoward seasons. Wherever a burst of water appears in any particular spot, the sure and certain way of getting quit of such an evil is to dig hollow drains to such a depth below the surface as is required by the fall or level that can be gained, and by the quantity of water expected to proceed from the burst or spring.

Having ascertained the extent of water to be carried off, taken the necessary levels, and cleared a mouth or loading passage for the water, begin the drain at the extremity next to that leader, and go on with the work till the top of the spring is touched, which probably will accomplish the intended object. But if it should not be completely accomplished, run off from the main drain with such a number of branches as may be required to intercept the water, and in this way disappointment will hardly be experienced. Drains, to be substantially useful, should seldom be less than three feet (1 m) in depth, twenty or twenty four inches thereof to be close packed with stones or wood, according to circumstances. The former are the best materials, but in many places are not to be got in sufficient quantities; recourse therefore, must often be made to the latter, though not so effectual or durable.

It is of vast importance to fill up drains as fast as they are dug out; because, if left open for any length of time, the earth is not only apt to fall in but the sides get into a broken, irregular state, which cannot afterwards be completely rectified. A proper covering of straw or sod should be put upon the top of the materials, to keep the surface earth from mixing with them; and where wood is the material used for filling up, a double degree of attention is necessary, otherwise the proposed improvement may be effectually frustrated.

The pit method of draining is a very effectual one, if executed with judgment. When it is sufficiently ascertained where the bed of water is deposited, which can easily be done by boring with an auger, sink a pit into the place of a size which will allow a man freely to work within its bounds. Dig this pit of such a depth as to reach the bed of the water meant to be carried off; and when this depth is attained, which is easily discerned by the rising of the water, fill up the pit with great land-stones and carry off the water by a stout drain to some adjoining ditch or mouth, whence it may proceed to the nearest river.

Modern drainage systems incorporate geo textile filters that retain and prevent fine grains of soil from passing into and clogging the drain. Geo textiles are synthetic textile fabrics specially manufactured for civil and environmental engineering applications. Geo textiles are designed to retain fine soil particles while allowing water to pass through. In a typical drainage system they would be laid along a trench which would then be filled with coarse granular material: gravel, sea shells, stone or rock. The geo textile is then folded over the top of the stone and the trench is then covered by soil. Groundwater seeps through the geo textile and flows within the stone to an outfall. In high groundwater conditions a perforated plastic (PVC or PE) pipe is laid along the base of the drain to increase the volume of water transported in the drain.

Enzymatic drain cleaners can be a safer alternative to chemical drain cleaners, and are easier on the environment. They use bacteria or enzymes, which naturally feed on organic waste, such as hair and food waste that often block drains. These tiny organisms, then digest the waste and to recreate beneficial bacteria and enzymes throughout the septic system. In fact, drain cleaners enzyme originally used to clean septic tanks and sewage. Enzymatic drain cleaners are better for the environment because they prevent hazardous chemicals that may leak into soil and water from spreading.

Alternatively, prefabricated plastic drainage systems made of HDPE called Smart Ditch, often incorporating geo textile, coco fiber or rag filters can be considered. The use of these materials has become increasingly more common due to their ease of use which eliminates the need for transporting and laying stone drainage aggregate which is invariably more expensive than a synthetic drain and concrete liners.

Over the past 30 years geo textile and PVC filters have become the most commonly used soil filter media. They are cheap to produce and easy to lay, with factory controlled properties that ensure long term filtration performance even in fine silty soil conditions.

Seattle's Public Utilities created a pilot program called Street Edge Alternatives (SEA Streets) Project. The project focuses on designing a system "to provide drainage that more closely mimics the natural landscape prior to development than traditional piped systems". The streets are characterized by ditches along the side of the roadway, with plantings designed throughout the area. An emphasis on non curbed sidewalks allows water to flow more freely into the areas of permeable surface on the side of the streets. Because of the plantings the run off water from the urban area does not all directly go into the ground but can also be absorbed into the surrounding environment.

The civil engineer or site engineer is responsible for drainage in construction projects. They set out from the plans all the roads, Street gutters, drainage, culverts and sewers involved in construction operations. During the construction of the work on site he/she will set out all the necessary levels for each of the previously mentioned factors.

Site engineers work alongside architects and construction managers, supervisors, planners, quantity surveyors, the general workforce, as well as subcontractors. Typically, most jurisdictions have some body of drainage law to govern to what degree a landowner can alter the drainage from his parcel.

Plumbing is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters. The plumbing industry is a basic and substantial part of every developed economy due to the need for clean water, and proper collection and transport of wastes. Plumbing also refers to a system of pipes and fixtures installed in a building for the distribution of potable water and the removal of waterborne wastes. Plumbing is usually distinguished from water and sewage systems, in that a plumbing system serves one building, while water and sewage systems serve a group of buildings or a city.

Plumbing was extremely rare until the growth of modern cities in the 19th century. About the same time public health authorities began pressing for better waste disposal systems to be installed. Earlier, the waste disposal system merely consisted of collecting waste and dumping it on ground or into a river. Standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 B.C.[2] Plumbing originated during the ancient civilizations such as the Greek, Roman, Persian, Indian, and Chinese civilizations as they developed public baths and needed to provide potable water, and drainage of wastes. The Romans used lead pipe inscriptions to prevent water theft. Improvement in plumbing systems was very slow, with virtually no progress made from the time of the Roman system of aqueducts and lead pipes until the 19th century. Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches and cesspools. Most large cities today pipe solid wastes to treatment plants in order to separate and partly purify the water before emptying into streams or other bodies of water. For potable water use, galvanized iron piping was commonplace in the United States from the late 1800's until around 1960. After that period, copper took over, first with soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings. The use of lead for potable water declined sharply after World War II because of the dangers of lead poisoning. At this time, copper piping was introduced as a better and safer alternative to lead pipes. Another material used for plumbing pipes, particularly water main, was hollowed wooden logs wrapped in steel banding. Logs used for water distribution were used in England close to 500 years ago. The US cities began using hollowed logs in the late 18th through the 19th centuries.

Water systems of ancient times relied on gravity for the supply of water, using pipes or channels usually made of clay, lead, bamboo, wood or stone. Present-day water-supply systems use a network of high-pressure pumps, and pipes are now made of copper, brass, plastic, or other nontoxic material. Present-day drain and vent lines are made of plastic, steel, cast-iron, and lead. Lead is not used in modern water-supply piping due to its toxicity. The "straight" sections of plumbing systems are of pipe or tube. A pipe is typically formed via casting or welding, where a tube is made through extrusion. Pipe normally has thicker walls and may be threaded or welded, where tubing is thinner-walled and requires special joining techniques such as "brazing", "compression fitting", "crimping", or for plastics, "solvent welding".

Plumbing equipment, not present in all systems, include, for example, water meters, pumps, expansion tanks, backflow preventers, filters, water softeners, water heaters, wrenches, heat exchangers, flaring pliers, gauges, and control systems. Now there is more equipment that is technologically advanced and helps plumbers fix problems without the usual hassles. For example, plumbers use video cameras for inspections of hidden leaks or problems; they use hydro jets, and high pressure hydraulic pumps connected to steel cables for trench-less sewer line replacement.

The major categories of plumbing systems or subsystems are:
  1. Potable cold and hot water supply
  2. Traps, drains, and vents
  3. Septic systems
  4. Rainwater, surface, and subsurface water drainage
  5. Fuel gas piping
  6. For their environmental benefit and sizable energy savings hot water heat recycling units are growing in use throughout the residential building sectors. Further ecological concern has seen increasing interest in grey-water recovery and treatment systems.

[1] Water Supply; From: (Retrieved April 30, 2011)
[2] Drainage; From: (Retrieved April 30, 2011)
[3] Water Supply Network; From: (Retrieved April 30, 2011)
[4] Ibid 2