Plumbing and drainage drawings in Wandsworth

Terraces, basements and long Victorian plots

Wandsworth has 137,393 households, of which 31.4 per cent live in a house or bungalow and 42.5 per cent own. An average terraced house costs £970,844, so basement and side-return projects are common, and each one disturbs the drains.

A basement is the heaviest drainage job. The Basement extensions guidance (non-statutory) covers the principle, and the Housing SPD (covers rear extensions, basements, roof extensions and loft conversions) sets the wider design guidance. Below-ground bathrooms discharge by a pumped system above the sewer level, with a non-return valve as the defence against surcharge. We draw the pump chamber, its rising main and the point where it joins gravity drainage.

Gardens cover 21.5 per cent of the borough's land, so long rear plots can take a soakaway where the ground drains. Ground conditions vary, so a trial pit comes first.

Building over drains and sewers

Extensions that cross a drain are the most common surprise. Approved Document H advises against building over a drain deeper than 3 metres, and the sewerage undertaker normally has to agree to a build-over. We mark the line, the depth and the offset on the plan and show the protection proposed.

Connections are governed by the Water Industry Act: the undertaker has 21 days to respond to a connection notice. A one-hundred-and-fifty-millimetre drain can be laid at 1 in 150 (minimum 5 WCs), a far shallower fall than a domestic branch needs, which explains many levels problems on shared runs.

Heritage, water use and efficiency

The borough has 46 conservation areas, 312 listed entries and 8 Heritage at Risk entries. Where a pipe would be seen from the street, we route it inside. A new dwelling also needs to meet the water efficiency figure, 110 litres per person per day where the optional requirement applies, so we choose fittings to match.

Quote and checking

For a Wandsworth job you get the two drainage networks on one plan, a long section through the lowest run with its falls, invert levels for every manhole, and a plain-English note on how the scheme meets the borough's SuDS policy. That is enough for a contractor to tender and for building control to inspect.

Wandsworth's busy planning service handled 977 householder decisions in the latest twelve months, so the officer who reads your drainage note has seen many. A clear one is a courtesy to them and shortens the questions you get back.

We publish no starting price. After a free constraints check you receive a fixed quote. We draw and specify and do not install. No Wandsworth set leaves us until a second technologist has checked it. Read the national guide, plumbing and drainage drawings, or the borough page, architectural drawings in Wandsworth.