The Mains Water Supply
Water to our homes is supplied by the various regional Water Suppliers. They’re responsible for delivering ‘potable’ water – basically clean wholesome water - that is fed via the water mains to our homes. The water we receive may go through a number of processes to make sure it is clean and fit for drinking. These include filtering, chlorination, and the addition of fluoride. The Water Supply Regulations (1999) set out rules and regulations to ensure, among other things, that water does not become contaminated and is not wasted
Mains water pipes
Trunk mains run underground to supply a series of principal and local mains. These are buried at sufficient depth to make sure that they are not affected by freezing or vibration – for example heavy lorries travelling along roads under which the mains are buried. The local main running under your street is often referred to as the Company Main and it’s the one to which your incoming water supply pipe is connected.
Water mains used to be made from asbestos cement, or cast iron. Nowadays PVC is used – you will see these blue pipes where new or replacement mains are being laid.
Connection to the Company Mains
Connection to the local main is made via special isolating valves which can be added without having to switch off the supply to the rest of the road. This allows a supply to a new house to be made without interfering with the water to other buildings in the road.
Supply to the House
A water pipe is laid underground from this valve to just outside the property’s boundary where an external stop valve is fitted. This section is referred to as the Communication Pipe and is the responsibility of the Water Supplier. Access to the stop valve is provided by an access chamber. This is a vertical pipe and has a cover at the top usually marked to make identification easier. From this stop valve the supply pipe continues towards the house and this part is referred to as the Service Pipe which is the responsibility of the home owner. The Service Pipe might be made from PVC, copper, lead or galvanised steel but modern pipes are normally medium density polyethylene (MDPE). This Service Pipe continues underground until it is inside the building. The depth of this pipe will be at least 750 mm to protect it from frost. The size of the pipe has to be at least 15mm but is commonly 25mm. The Service Pipe should be sleeved where it passes under the building and, as it rises up it will also be insulated to protect it from frost damage.
The water meter may be fitted externally or internally. Where it is fitted outside the property, it is generally found inside a protective chamber and includes a stop valve enabling the supply to be isolated at this point. Internal water meters are fitted close to the point where the supply goes into the house and there will also be a stop valve. This valve allows water to the house to be isolated in the event of an emergency or for maintenance. There will also be a drain valve here which allows for the system to be fully drained if needs be.