This document provides information about water supply systems for buildings. It discusses the sources of water, including surface water sources like rivers and lakes, and groundwater sources like aquifers. It then describes direct and indirect cold water supply systems for buildings. A direct system supplies water directly from the mains to outlets, while an indirect system uses a storage cistern. The document recommends an indirect system to provide a reserve supply and reduce pressure on pipes. It also discusses water treatment methods, mains water supply, and tanks used for water storage in buildings.

1. BUILDING SERVICE
Assaignment on “WATER SUPPLY SYSTEM”
Submitted by-
Abdullah Al Hossain
ID:ARC 05405607
Jannatul fardous
ARC05405597
Submitted to-
Mashudur Rahman Fahim
STAMFORD UNIVERSITY BANGLADESH
D E P A R T M E N T O F A R C H I T E C T U R E
S

2. WATER IS
colourless, transparent, odourless, liquid which forms the seas, lakes, rivers, and rain and is the
basis of the fluids of living organisms
Water is a polar inorganic compound that is at room temperature a tasteless and odorless liquid,
nearly colorless with a hint of blue.
Density: 1,000 kg/m³
Formula: H2O
Boiling point: 100 °C
Molar mass: 18.01528 g/mol
Melting point: 0 °C
IUPAC ID: Water, Oxidane
Water is very important for life. We need water to drink, to wash our hands, to cook,
to water plants and many other things
fig: Water recycling process

3. Sources of water:
There are two main sources of water:
1.Surface water
2.Groundwater.
Surface Water is found in lakes, rivers, and reservoirs.
Groundwater lies under the surface of the land, where it travels through and fills openings in
the rocks. The rocks that store and transmit groundwater are called aquifers.
Fig : Surface Water Fig : groundwater
Natural sources of water
Water comes from three main natural sources: rain water, underground water and surface water. Rain water
includes rain, snow and other forms of precipitation. Underground includes water tables and water hidden in
the soil. Surface water includes oceans, rivers, lakes, ponds and any other above-ground collection of water
These natural sources of water supply most of the water for the planet. Precipitation replenishes
underground and surface water supplies and is a key part of the water cycle. Underground water sources are
not immediately accessible but are one of the most important sources of water for human consumption.
Underground water supplies areaccessed through wells, or from springs when the pressure gets too great.
Surface water is the easiest to access and the most abundant, though most surface water is salt water, and,
therefore, not suitable for drinking by most species. Surface water is used for drinking and for producing
hydro-electric power as a renewable, clean energy source. This water comes from precipitation, springs and
the melting of glaciers. Rivers eventually empty into the ocean.

4. A large portion of fresh water is trapped in glaciers, the ice caps and the atmosphere. The frozen water is not
accessible directly by humans, but it does help to replenish surface water supplies as the global temperature
rises and the ice melts
https://www.reference.com/geography/natural-sources-water-29b79a6c47d6aea
Cold water
1. Drinking purpose.
2. Cooking purpose.
3. Sanitarypurpose.
4. Washing purpose.
5. Gardening
Hot water
is supplied by gas fired or electric heaters
Cold water pipes should be insulated and covered
with a vapor barrier to prevent surfacecondensation
and heat flow into the water from the warmer
surroundingair.
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WATER SUPPLY

5. Water supply is the provision of water by public utilities commercial organisations, community endeavors or
by individuals, usually via a system of pumps and pipes. Irrigation is covered separately.
A watersupply systemorwater supply networkisasystemof engineeredhydrologicandhydraulic
componentswhichprovidewatersupply.A watersupply systemtypicallyincludes:A drainage basin
(see waterpurification - sources of drinkingwater).
Fig: WATER SUPPLY Fig: WATER SUPPLY
An arrangement of reservoirs, purification plant, distribution pipes, etc, forproviding water to a
community |
Two types of water supply systems;
non storage or direct and
storage or indirect systems
Direct System
In a direct system water is supplied at mains pressure to all coldwater taps/faucets, WC (toilets)
cisterns and a cold waterstorage cistern/tank if hot water is to be supplied from an open vented
(lowpressure)hotwater cylinder.

6. This is an 'unbalanced' cold water system because the coldwater outlet pressure at taps/faucets is
higher than the hot water from the open vented cylinder.
To have a balanced coldwater system the cold water storage cistern must be removed and the open
vented hot water cylinder replaced witha mains pressure supplied unvented hot water cylinder.
The pipe circuitfor cold water distribution in the home branches off after the pressure reducing
valveon the supply pipe thereby balancing the system enabling equal cold and hot water pressure
at all draw-offs(outlets).
However,the trade off with the use of an unvented cylinder is that youno longer have stored cold
water fortoilet flushing in the event of a mains water failure.
With a direct cold water system youhave the advantage of being able to draw drinking water from
any cold water taps/faucets in the house
Indirect System
An indirect cold water system is when water is supplied to the house at mains pressure, this water
is fed directly to a cold water storage cistern via the supply pipe called the 'rising main'.
A branch pipe off the rising main delivers drinking water to the kitchen and garden tap/faucet, cold
water to all other taps/faucets and appliances is provided indirectly fromthe cold water storage
cistern (not for drinking)under gravity pressure not mains pressure.
The hot water storage cylinder is also supplied with cold water fromthe same cistern.
With an indirect coldwater system there is always a temporary back up of stored water in the event
of a mains failure. Also, because it is a low pressure system it is generally quieter therefore
eliminating noise like 'water hammer' whichcan occurwhen high pressure water tries to negotiate
tight bends in the pipework.
Indirect cold water systems do slightly reduce the risk of impure water being siphoned backinto
the mains water supply by having feweroutlets (taps/faucets andappliances) connectedto the
mains supply.
However,this can easily be protected against in both the direct and indirect cold water system by
installing a non-return valveor checkvalve immediately after the main stop-valvesupplying water
to the house. This wouldbe good practice.
A non-returnorcheck valveonlypermits waterto flow throughit in onedirection
Note: Fitting a drain valve after (downstream) thenon-return valveafter the main stop-valvewill
enable draining of the rising main pipe.

7. Utilization of Water in Buildings:
Consumed by drinking, cooking, [Must be Portable]
washing etc.
Circulated by heating and cooling [Soft and Neutral]
system.
Stored by fire protection system. [No Requirements]
Controlled to maintain desirable
humidity level.
Table 1.4 Estimation of cold water storage per occupant
Type of building Storage per occupant (litres)
Hospitals, per staff on duty 45
Hostels 90

8. Hotels 135
Houses and flats 135
Offices with canteens 45
Offices without canteens 35
Restaurant (* per meal) 7
Schools, boarding 90
Schools, day 30
Water Supply, Storage and Distribution
Water supply
Precipitation
Precipitation is the main source of water for drinking purposes. A percentage of rainfall evaporates soon
after it falls, a percentage runs off the ground to join streams and rivers and a percentage seeps through
the ground to join underground supplies.
Sources of water supply consist of surface water and underground water.
Surface water
This includes water collected from roofs and paved areas as well as streams, rivers, lakes and reservoirs.
This water is liable to contamination by vegetation and farm pollutants. Sewage and industrial waste are
sometimes fed into rivers without any purification treatment. These same rivers are usually expected to
supply fresh water for towns and villages. Rivers have the ability to purify themselves, especially if they
are fast flowing and shallow. Despite this ability water taken from a river for public use should be treated
before consumption.
Underground water
Rain that seeps through the ground may eventually reach an impervious layer, where it may be held as in

9. a reservoir or it may flow like an underground stream on top of the impervious layer. Layers of 'water' are
called aquifers.
Springs
There are two types of springs. A main spring which is usually deep and connects to the aquifer layer and
a shallow or simple spring which connects to underground surface water. The latter is likely to be
intermittent. Spring water is usually pure resulting from the natural purification that occurs as the water
permeates through the ground.
Wells
Wells are different to springs as the ground has to be bored to reach the water. Springs occur naturally.
The upper part of a well must be lined to exclude surface water entering it as it may be polluted.
Water treatment
Water to be used in a public water supply is required to be fit for drinking. This implies that it poses no
danger to health, and it should be colourless, clear, odourless, sparkling and pleasant to taste. There are
four main techniques used for the treatment of water. They are:
1. Storage
2. Filtration
3. Sterilisation
4. Softening
Storage
Water is stored in reservoirs where contaminants/impurities settle to the bottom (sedimentation).
Pathogenic bacteria (disease producing) find it difficult to survive in storage due to the lack of food, low
temperatures and the effect of sunlight. If water is stored for long periods, algae tend to grow. The growth
of algae can be controlled using chemicals such as copper sulphate.
Filtration
Water is passed through sand or a fine wire mesh to remove particles. Rapid sand filters act as a physical
filter, leaving the water in need of chemical treatment. Slow sand filters provide physical and chemical
action. In a slow sand filter water slowly percolates down through the sand. Fine particles, micro-
organisms, and microscopic plant life are retained in the sand bed. The bed must be emptied for cleaning
after a number of weeks. The slow sand filter produces high quality water, which needs little further
processing.

10. Sterilisation
Water must be sterilised before it can be consumed by humans. Chlorine is added to the water for public
supply, but this isn't always feasible for small installations. Chlorine kills bacteria making the water safe to
drink. After sterilisation ammonia is sometimes added to the water to reduce the offensive taste left by the
chlorine. For smaller installations water is passed through a very fine filter capable of removing the
bacteria.
Softening
Hard water is recommended for drinking but it has disadvantages. Scale may be deposited in hot water
pipes and boilers, and soap does not make a lather.
There are a number of ways to soften water:
1. Base exchange methods change hardness compounds into compounds which do not cause hardness.
2. Demineralisation is a process to remove all chemicals dissolved in the water.
3. Lime-Soda treatment depends on chemical reactions to make the calcium and magnesium in the hard
water insoluble and they are then removed.
Mains Water Supply
Most dwellings and buildings, including those in rural areas are supplied with water from a public water
supply, otherwise known as the mains supply. The design of a mains water supply needs to consider
present demand and anticipated future demand, the size of the water mains, and the pressure of water in
the mains (this is known as the 'head', the height to which the water would rise in a vertical pipe.
The standard size for a water mains is 75 mm diameter if it is supplied from both ends and 100 mm if it is
supplied from one end only. 30 m is the minimum head of water recommended for fire fighting purposes,
while a head of 70 m is recommended to minimise waste and reduce noise in pipes. The head is
achieved by locating reservoirs at appropriate heights above the buildings being served. Full pressure
(head) from the reservoir is seldom available as flow in the mains will be taking place at most times.
Pressure is further reduced by friction due to flow.
The water mains is usually sited along the edge of a roadway. Permission must be obtained to connect to
the mains and to cut the road if this is necessary. A domestic connection consists of a 12 mm diameter
pipe with a minimum cover of 750 mm below ground as protection from frost.

11. Cold water storage and distribution
Introduction:
The connection to the mains water supply is usually taken to the boundary of the siteand finished with a stop
valveor stop cock,housed in a suitablebox or purpose chamber. This chamber may be fitted with a hinged cast
iron cover. The cold water supply for the dwellingis taken from the stop valveto the building,750 mm below
ground level. A second stop valveshould be fitted on the servicepipe where it enters the building.Where possible
this should be at the kitchen sink,although the location is notcritical.Insidethe house a drain cock should be
fitted above the stop valveto allowthe cold water system to be drained down.
There are two main types of cold water supply systems within the house. These areknown as 'direct' and 'indirect'.
Direct cold water supply system
In this system water from the cold water servicepipe feeds all the cold water outlets includingthe sanitary
appliances.
This system may be found in old houses, but otherwise it is not recommended for the followingreasons:
1. In the event of mains failurethere is no reserve.
2. Mains supply exerts increased pressureon fittings.
3. Duringpeak demand the pressuremay be reduced.
Advantages of this system include:
1. Economical on pipework
2. Only a small cold water storagecistern required to feed the hot water tank.
3. Drinkingwater availablefromall thecold water outlets.
Cold Water Storage and Distribution:

12. Indirect cold water supply system In this system all cold water outlets with the exception of one drinking
water outlet are supplied indirectly from a cold water storage cistern, usually located in the roof space.
'Indirect' means the water is not coming directly from the mains to the outlets, it is piped to and stored in
the cistern in the attic.
Advantages of this system:
1. A reserve supply in case of mains failure.
2. Less pressure on the taps and valves resulting in less wear.
Disadvantages of this system:
1. More pipework required.
2. Provision and installation of a storage cistern in the attic.
This is the most common system used.
Fig:WATER SUPPLY
Water supply system usually accommodated within:

13. Floors
Wall construction
Water Distribution:
Tanks Used for storage :
Ground or underground storage tank
Pressure control method :
Zoning floors by Intermediate tanks
Using pressure reducing valve
Water Tanks :

14. Water Distribution: