QUICK GUIDE: MAINS WATER CONNECTIONS

It is the water authority’s responsibility (at your cost) to make any connections from their main to your site boundary but, thereafter, the supply pipe responsibility to your dwelling is yours. Most properties now have a water meter and the first restriction in your eventual supply is the diameter of the water authority’s pipe between their meter and their main.

New supplies are usually delivered in 25mm pipework (external dimensions), which is adequate for many self build properties. However, at an extra cost, these can be increased to 32mm, 50mm or 63mm. If you’re building a house with three or more bathrooms and you want all of the showers to operate simultaneously without a significant loss of pressure, then you’ll need a greater water main diameter and confidence that the authority’s pipe pressure is adequate. All of this can (and should) be checked and agreed at the design stage.

If the water supply is poor, then the designer can compensate with pressurised accumulator tanks, which can subsequently deliver the hot water pressures and capacities you want. They are bulky and add more cost, so you need to factor this in right at the start.

In the case of an existing house, old water supplies could be in lead, steel or copper, and might feature multiple different pipe diameters. Over many years, they may have furred up and their effective internal diameter could be reduced. Good maintenance will minimise such issues – but ultimately the pipework might need replacing.