Underground cold water service pipe installation depth and entry

The service pipe carries water from the distribution main towards the building. Its route, material and protection must suit the ground conditions and the water undertaker's requirements. Blue MDPE is common, but ordinary plastic pipe is not suitable for every contaminated site.

Depth and exceptions

Water Regs UK guidance gives a normal depth range of 750–1350 mm. Shallower pipework needs protection against freezing and mechanical damage. If an obstruction prevents the normal depth, consult the local water undertaker: installation outside that range requires its agreement. Do not attribute these dimensions to a universal Approved Document G rule.

Worked decision: an existing service crosses the proposed route at 650 mm. Simply routing the water pipe over it would put the water pipe outside the normal range. Agree a suitable route or protected arrangement before laying it; insulation alone does not remove the consent requirement.

Entering the building

Use the undertaker's entry detail for the wall or floor construction. Protect the pipe against damage, heat gain and freezing, with suitable ducting, sealing and insulation where required. Avoid an unprotected rise through a cold void. The position of the thermal envelope and other services matters; passing the outside wall is not by itself proof of frost protection.

Ground and materials

Consider fuel, oil and other ground contamination when selecting the pipe system. Use suitable compatible fittings, and keep pipe interiors clean during installation. Agree notification and inspection arrangements before covering the work.

The depth range is one design check. It does not establish that the ground, entry detail, pipe material or separation from other services is acceptable.