INTRODUCTION OF WATER SUPPLY SYSTEM

Water supply system, infrastructure for the collection, transmission, treatment, storage,

and distribution of water for homes, commercial establishments, industry, and irrigation, as well

as for such public needs as firefighting and street flushing. Of all municipal services, provision

of portable water is perhaps the most vital. People depend on water for drinking, cooking,

washing, carrying away wastes, and other domestic needs. Water supply systems must also meet

requirements for public, commercial, and industrial activities. In all cases, the water must fulfill

both quality and quantity requirements.

A water supply system is a network of pumps, pipelines, storage tanks, and other

appurtenances. It must deliver adequate quantities of water at pressures sufficient for operating

plumbing fixtures and firefighting equipment, yet it must not deliver water at pressures high

enough to increase the occurrence of leaks and pipeline breaks. Pressure-regulating valves may

be installed to reduce pressure levels in low-lying service areas. More than half the cost of a

municipal water supply system is for the distribution network. A sustainable urban water supply

network covers all the activities related to provision of potable water. Sustainable development is

of increasing importance for the water supply to urban areas.

Water is an essential natural resource for human existence. It is needed in every industrial

and natural process, for example, it is used for oil refining, for liquid-liquid extraction in hydro-

metallurgical processes, for cooling, for scrubbing in the iron and the steel industry and for

several operations in food processing facilities etc. It is necessary to adopt a new approach to

design urban water supply networks; water shortages are expected in the forthcoming decades

and environmental regulations for water utilization and waste-water disposal are increasingly

stringent. To achieve a sustainable water supply network, new sources of water are needed to be

developed, and to reduce environmental pollution.

The price of water is increasing, so less water must be wasted and actions must be taken

to prevent pipeline leakage. Shutting down the supply service to fix leaks is less and less

tolerated by consumers. A sustainable water supply network must monitor the freshwater

consumption rate and the waste-water generation rate. Many of the urban water supply networks

in developing countries face problems related to population increase, water scarcity, and

environmental pollution.

Requirements of Good Distribution System

Water quality should not get deteriorated in the distribution pipes.

It should be capable of supplying water at all the intended places with sufficient pressure

head.

It should be capable of supplying the requisite amount of water during fire fighting.

The layout should be such that no consumer would be without water supply, during the

repair of any section of the system.

All the distribution pipes should be preferably laid one metre away or above the sewer

lines.

It should be fairly water-tight as to keep losses due to leakage to the minimum.

Methods of water supply system

The method of water supply system for efficient distribution system adequate water pressure

required at various points. Depending upon the level of source, topography of the area and other

local conditions the water may be forced into distribution system by following ways :

1. Gravity system

This system is suitable when source of supply is at sufficient height. It is most reliable and

economical distribution system. The water head available at the consumer is just minimum

required. The remaining head is consumed in the frictional and other losses.

2. Pumping system

The treated water is directly pumped in to the distribution main with out storing. It is also called

pumping without storage system. The high lifts pumps are required. If power supply fails,

complete stoppage of water supply.This method is not generally used.

3. Combined gravity and pumping system

This combined system is the most common system. The treated water is pumped and stored in an

elevated distribution reservoir. Then supplies to consumer by action of gravity. The excess water

during low demand periods get stored in reservoir and get supplied during high demand period.

Economical, efficient and reliable system.

System layout and pipework

The water supply system must be designed to achieve appropriate water pressure and flow, and

to avoid contamination to potable water.

Water pressure

Water flow rate

Flow rate and pipe size Acceptable Solutions

System layout

Connection to the mains supply

Backflow

Mains connection

Pipe materials and specifications

As well as avoiding contamination and achieving the right pressure and flow, the system must be

suitable for the temperature of water carried. A well-designed and installed system will also be

durable, minimise noise from water flow and from problems such as water hammer, and support

efficient use of water.

All water supply systems use a combination of pipes (of different dimensions and materials),

valves and outlets to deliver water to building users. Some water supply systems also use storage

tanks and pumps. Designing a water supply system involves getting all of these elements right so

that clean water is delivered to the user at the appropriate rate and temperature.

Water pressure

If the aim is to provide for building users’ needs while also using water efficiently, the

right water pressure is crucial. If water pressure is too low, this will be inconvenient for building

users for example, because showers have poor water flow, and baths take a long time to fill. If

pressure is too high, this will lead to wastage of water, as well as high wear and tear on the

system.Typically, new buildings in areas with mains water supply will have mains pressure

systems. Existing buildings, and buildings that are not connected to mains water, may have low

pressure systems or unequal pressure systems (with different pressures for hot and cold water

supply).

As an example of the difference in water usage, a low pressure hot water system shower

flow may average about 7 litres per minute, while a mains pressure shower may average about

12.5 litres per minute.Mains pressure systems require pressure limiting and pressure reducing

valves to control water pressure and temperature. Typically, pressure limiting or pressure

reducing valves will be used to control pressure in mains-supplied hot water systems or where

high pressure may lead to problems such as burst pipes.

Low pressure systems require few valves or controls. In low or unequal pressure systems,

pressure can be increased to adequate levels by storing water in a header tank (typically in the

ceiling space) so that gravity can be used to create water pressure. Pressure can also be raised to

adequate levels using a pressure rising pump, in which case it may be necessary to use pressure

limiting and pressure reducing valves.

System layout

In the design process, the layout of the plumbing system will largely follow room layout.

Nonetheless, there are many things to consider which relate to Code compliance, building users’

comfort, and sustainability.

When planning a water supply layout, the following must be considered:

Pipe runs and lengths – Keep pipe runs as short as possible. Pass pipes close to fixtures

to minimise the number of branches and unnecessary elbows, tees and joints. Having

longer pipe runs and more fixtures will reduce flow rate, increase heat losses, and

increase use of materials

Point of entry into the building – This should be into a utility space such as

garage/laundry and include an accessible isolating valve, line strainer and pressure

limiting valve (if required).

Water heating system – Locate centrally to reduce the length of pipe runs to fixtures

because longer pipe runs require more water to be drawn off before hot water is

discharged. Install a separate point-of-use water heater for fixtures that are more than 10

m from the main water heater

Noise prevention – Avoid running pipes over or near bedrooms and living areas.

Water supply layout

Backflow

Backflow is the unplanned reversal of flow of water (or water and contaminants) into the water

supply system. The system must be designed and used to prevent contamination from backflow.

See preventing backflow for more.

Mains connection

Where the water source is a mains supply, the network utility operator is responsible for the

water supplied to the property boundary. The property owner is then responsible for providing

the pipework to bring the water into the building. An isolating valve must be fitted at the point of

connection to allow for maintenance and repair of the building’s water supply system if required.

Pipe materials and specifications

The pipes used in a building must not contaminate potable water supply, and must be suitable for

the water pressure, flow rate and temperature of water they will be carrying. This will be

influenced by the materials used and also by other factors such as the wall thickness.

Indirect water supply

Water going to overhead tank and then the water is supplied to different floors by gravity.

Plumbing system

Plumbing is the system of pipes, drains fittings, valves, valve assemblies, and devices

installed in a building for the distribution of water for drinking, heating and washing, and the

removal of waterborne wastes, and the skilled trade of working with pipes, tubing and plumbing

fixtures in such systems. A plumber is someone who installs or repairs piping systems, plumbing

fixtures and equipment such as water heaters and backflow preventers.

The plumbing industry is a basic and substantial part of every developed economy due to

the need for clean water, and sanitary collection and transport of wastes. The word "plumbing"

comes from the Latin plumbum for lead, as pipes were once made from lead. Plumbing is usually

distinguished from water supply and sewage systems, in that a plumbing system serves one

building, while water and sewage systems serve a group of buildings.

Technical terms used in plumbing

1) Soil pipe (soil line)

A pipe which conveys the discharge of water closets or fixtures having similar functions,

with or without the discharges from other fixtures.

2) Waste appliances

It includes wash-basins, sinks, bath-tubs washing trough drinking water fountain etc.

3) Waste pipe

A pipe that carries off liquid waste.

4) Rain water pipe

This is a pipe provided to carry rainwater.

5) Ventilation pipe(vent pipe)

Ventilates drainage pipe is open at the top and it is connected to a soil pipe or waste pipe at

its bottom. This pipe is extended above the roof of the building to permit exit of foul gases

into the atmosphere. This pipe only ventilates the system and doesn’t carry any discharge

from soil, waste or rain-water pipe.

Pipe materials for fitting

1. Copper

Copper has long been used for all types of domestic water services and distribution because

it:

is durable

has good corrosion resistance

is malleable and easy to bend

is self-supporting

has good flow characteristics

requires few fittings

can be recycled.

Copper may be annealed (i.e. heated, then cooled slowly) which improves its properties, for

example making it less brittle and stronger. Although copper in general has good corrosion

resistance, this depends on the environment. Acidic conditions, either from the soil (if buried) or

from the water, can cause corrosion, so local pH levels should be checked before using copper

pipes.

2. Polybutylene (PB)

Polybutylene is a plastic material that was introduced in the late 1970s and used extensively

for water supply pipes until the mid 1990s. Unfortunately, one brand of polybutylene gained

a reputation for failure, resulting in a significant drop in use.

Polybutylene has excellent properties for use as water supply pipework including:

low cost

flexibility

ease of installation

ability to be used for both hot and cold water services

frost resistance.

In outdoor situations, it must be protected from UV exposure.

3. Unplasticised polyvinylchloride (PVC-U or uPVC)

PVC-U is the most widely used plastic piping for water supply pipes and drainage pipes. It

can be used in internal, exposed outdoor and underground situations as it:

is durable

is inexpensive

has good flow characteristics

has chemical resistance

can withstand UV

is easy to handle.

It is suitable for cold water services and can be used for limited hot water services as it has a

maximum temperature use of 60°C (140°F).

Chlorinated polyvinyl chloride (CPVC or PVCc) is produced by the chlorination of PVC.

The result is a PVC pipe with a service temperature of 90°C (190°F) that may be used for hot

water supply pipes.

4. Polyethylene (PE or HDPE)

High density polyethylene (often called alkathene or polythene) has been used since the early

1960s. It is suitable for both potable water and wastewater services but it can only be used for

cold water supply. It is the most commonly used plastic pipe for supplying the mains water to

a dwelling. Polyethylene:

is durable

is corrosion resistant

has good flow characteristics

is lightweight and flexible

is easy to install

has a good bending radius

is inexpensive

requires few fittings.

5. Polypropylene (PP)

There are three types of polypropylene:

P-H has good mechanical properties and excellent chemical resistance for use as

industrial and sewerage waste pipes systems

PP-R has good resistance to high internal pressure so it is suitable for domestic pressure

water supply systems and both hot and cold water services

PP-B is suitable for buried sewerage and wastewater drainage as it has good impact

strength, particularly at low temperatures, and excellent chemical resistance.

The use of polypropylene has been increasing since the late 90s as it is:

chemical and corrosion resistant

heat resistant

lightweight

easy to install

frost resistant, In outdoor situations, it must be protected from UV exposure.

6. Cross-linked polyethylene (PEX)

PEX tubing is made from a cross-linked, high density polyethylene polymer, which results in

a stronger material that polyethylene. Properties include:

more durability under extremes of temperature and chemical attack

greater resistance to cold temperatures, cracking and brittleness on impact

it can be used for hot water supply and hydronic heating systems, as well as potable water

supplies

flexibility

ease of installation

it can be used for indoor and buried outdoor situations.

PEX is not recommended for outdoor above ground use – although it can withstand some

UV exposure, this should not exceed the manufacturer’s instructions.

Pipework installation

1. Responsibilities

Before a project starts, determine the responsibilities for specific work of the plumber, the main

contractor and the electrician.

Discuss the location of pipe runs with the main contractor to minimise cutting or notching of

framing.

2. General installation requirements

Pipework must:

Comply with the durability requirements of Building Code clause B2 Durability.

Be compatible with the support.

Be installed to allow for thermal movement.

Be protected from freezing by insulation, or being buried below the level of freezing.

Be protected from damage

Be wrapped in flexible material or sleeved when penetrating masonry or concrete.

Where to lay pipework

Pipework may be installed:

in a roof space

under a timber floor

below a concrete slab (BRANZ does not recommend within slab installation).

Where pipes are buried, they must have:

600 mm cover under trafficked areas

450 mm cover under lawns and garden areas (non-trafficked)

Where pipes are under concrete, they must have 50-year durability.

Sanitary system in housing

It is the arrangement provided in a house or building for collecting or conveying waste

water through drain pipes, by gravity, to join either a public sewer or a domestic septic tank is

termed as house drainage or building drainage. All the piping within the private and public

premises which conveys sewage, rainwater and other liquid waste to a point of disposal. A

drainage system does not include the mains of public sewer systems or a private or a public

sewage treatment or disposal plant.

Types of sanitary appliances

Fitting used for cleansing and disposing of waste product, most sanitary appliances fall into

two groups:

i. Waste appliances ( bidets, wash basins, sinks, showers / baths tubs , drinking fountains )

ii. Soil appliances ( water closet, urinal ).

Sanitary sytem in housing

1. Single Stack System

I. System where only 1 pipe is required and it does not need vent pipe as it can function as

vent pipe.

II. Discharge in branching pipes from sanitary fitting are transferred into single stack pipe.

III. The flow is then drained into the drainage pipe.

IV. The system is appropriate for multi-storey buildings.

V. Sanitary fitting should be installed near the single stack pipe to reduce the length of the

branching pipe and minimum the sound of flow in the pipe.

VI. The sanitary fitting should be connected to the single stack pipe separately.

VII. This system is easy to install.

2. Single Pipe System

1. Use only 1 pipe in

collecting and draining discharge.

2. All sanitary fittings are connected to 1 pipe only. Connection is made at the branching

pipe.

3. The single stack vent pipes release compressed air that may have trapped at the base of

waste and wastewater single stack pipe.

4. The vent branching pipe connects the single stack vent pipe to the sanitary fitting.

5. All sanitary fitting should be installed near a main pipe.

3. Dual pipe System

i. This system uses 2 single stack pipes, one for waste and the others is for soil.

ii. Both of the single stack pipes have individual ventilation system.

iii. The waste discharge pipe drains wastewater from the shower tray, WB and bathtub.

iv. The soil discharge pipe drains soil water from the WC and urinal.

v. The single stack pipe is then connected to the underground drainage pipe.

vi. This system is suitable when the waste fitting is located far from the waste water fitting.

Pipe

Comparison of sanitary discharge Pipe Systems

System Types of Pipes Advantages Disadvantages

Dual Pipe Waste single stack pipe

Soil single stack pipe

More effective drainage Require two types of pipe

Complicated installation work

Single Pipe Waste and soil single stack pipe

Vent pipe

Require only one main pipe

Easier to install

Vent pipe installation is complicated

Require more pipelines for vent pipe

Single Stack Waste and soil single stack pipe

Require only one single stack pipe

Ventilation is less efficient

Sanitary fittings

i. Wash basinsii. Sinks

iii. Bath tubsiv. Water closetsv. Urinals

vi. Flushing cisterns

Wash basins Sinks

Bath tubs Water closets

Urinals Flushing cisterns