Unit 307 Session 5 Distribution of cold water

​Distribution of cold water

​There are two methods of water supply distribution used in the UK. These are:

1 gravity distribution
2 pumped distribution

​Gravity distribution

The water from the collection of upland surface water is impounded in reservoirs on high ground. Here, the water is filtered by slow sand filters, and chlorinated before being fed to homes and factories by gravity.
No pumping is required.

​Pumped distribution

​When water is taken from a river, it is pumped direct to a settlement tank where all of the heavier impurities sink to the bottom. It is then passed through a slow sand filter to remove any organic matter and chlorinated to wholesome water standard before being pumped to a water tower.
From the tower, it flows via gravity to the water main.

Hotspot

Where is the service reservoir?

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Where is the Water main?

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Where is the Chlorinating house?

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Where is the slow sand filter?

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Where is the Water main?

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Where is the Settlement tank?

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Where is the River?

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Where is the Pump house?

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Where is the Service reservoir on a water tower?

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Where is the Slow sand filter?

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Where is the Chlorinating house?

​THE WATER SERVICE PIPEWORK TO DWELLINGS

​Distribution of water in cities, towns and villages

​Water is supplied to our homes via a grid system network of pipes known as trunk mains, a phrase dating back to when the mains were constructed from hollowed-out tree trunks.

​When a new house has to be connected to the water supply, the supply pipes are usually 25 mm (32mm in Wales) in diameter.

Open Ended

Why do you think there is a need for a 32mm main supply to houses in Wales?

​In Wales new dwellings and buildings that have had significant refurbishment must now have a fire sprinkler system installed, therefore it is usual for a 32mm water mains supply to be installed.

​Most water supplies in modern dwellings and industrial premises are piped in medium-density polyethylene pipe (MDPE), which is coloured blue for easy identification to show mains cold (potable) water.

​Methods of connection to the water main

Underneath the road is the water main. The connection for the water supply to the dwelling is made by a brass ferrule, which is the responsibility of the water undertaker. The ferrule is a type of shut-off valve that allows the water supply connection to be isolated for maintenance and repair.

​From the water main to the building

The water supply from the water main into the building comprises two separate pipes:

1 the communication pipe, owned and maintained by the water undertaker


2 the supply pipe, owned and maintained by the owner of the building.

​The water authorities recommend that no more than 150 mm of blue MDPE pipe be exposed above the floor level of the building. This is to minimise the amount of MDPE pipework visible because MDPE decomposes under persistent exposure to the ultraviolet (UV) light present in daylight.

​Entering the property

The water supply enters the property, it should terminate with a screw-down stop tap/valve complying with BS 1010-2

​The Defra guidance to the Water Supply (Water Fittings) Regulations 1999 is very specific: As far as is reasonably practicable:

1 A stop valve should be located inside the building; and,
2 Be located above floor level; and,
3 As near as possible to the point where the supply enters the building; and, 4 Be so installed that its closure will prevent the supply of water to any point in the premises.

​There are many different stop valve/tap styles available that are manufactured to BS 1010-2.

​A drain-off valve conforming to BS EN 1254 should be installed immediately above any stop tap/valve to allow draining of the system.

​Test yourself

Labelling

Label the diagram

Drag labels to their correct position on the image

750mm min-1350mm max

Communication pipe

Service pipe

Multiple Choice

In the UK, what are the two main methods of water supply distribution?

• Pressure and Gravity

• Gravity and Pumped

• Flow and Pumped

• Pressure and Flow

Multiple Choice

How is water impounded in reservoirs on high ground typically filtered in gravity distribution?

• Reverse osmosis

• Slow sand filters

• Activated carbon filters

• UV treatment

Multiple Choice

What is a key advantage of gravity distribution mentioned in the description?

• Lower energy consumption

• Faster water flow

• Reduced filtration requirements

• Higher pressure control

Multiple Choice

In pumped distribution, where is water pumped after being taken from a river?

• Settlement tank

• Water tower

• Slow sand filter

• Reservoir

Multiple Choice

What is the purpose of slow sand filters in water treatment?

• Removal of heavy impurities

• Disinfection with chlorine

• pH adjustment

• Sedimentation

Multiple Choice

Which material is commonly used for water supply pipes in modern dwellings and industrial premises?

• Copper

• PVC

• Medium-density polyethylene (MDPE)

• Steel

Multiple Choice

What is the recommended maximum exposure of blue MDPE pipe above the floor level of a building?

• 100 mm

• 150 mm

• 200 mm

• 250 mm

Multiple Choice

According to Defra guidance, where should a stop valve be located inside a building?

• Below floor level

• Within ground level

• Above floor level

• Near the roof

Multiple Choice

Which pipes are typically owned and maintained by the owner of the building in the water supply connection?

• Communication pipe

• Service pipe

• MDPE pipe

• Ferrule pipe