Leak Detection in South West London

An SES Water Pocket in a Thames Water Region

Nearly all of South West London is on Thames Water, which is why the exception catches people out. Much of Sutton, taking in Cheam, Carshalton, Wallington and Hackbridge, is supplied by SES Water instead, and Morden sits at the northern edge of that same area. The name on the bill is the reliable test, and it decides who you report a burst in the road to and which leak allowance scheme applies afterwards. SES Water draws largely on chalk groundwater, so the supply is hard and scale builds on valves until a stop tap no longer closes fully, which is worth mentioning when you book because it slows every isolation test.

Both companies draw the same boundary. The main and the connection up to the boundary stop tap are theirs, and the supply pipe from there into the house is the owner's, shared where it feeds more than one home. Homes built before about 1970 may still have lead on that run, and Thames Water operates a replacement scheme that is worth knowing about if a leak turns up on an old lead length. A buried supply pipe survey is £300 to £500.

Cottage Estates, Terraces and Mansion Blocks

The London County Council left its mark all over this area. Totterdown Fields in Tooting, begun in 1901, was the first LCC cottage estate and holds over a thousand small houses. St Helier followed between 1928 and 1936, spreading across the Morden and Carshalton boundary once the Underground reached Morden in 1926.

The mansion blocks are a case of their own, notably the five storey ranges along Prince of Wales Drive looking out over Battersea Park, where risers are communal and the long flat runs between them let a failure on one level mark the ceiling of another. In every one of these buildings the useful question is not where the stain is but which pipe and which home it belongs to, and a trace and access survey at £350 to £450 answers it in writing.

Screed, Underfloor Heating and Riverside Towers

The newest housing behaves nothing like the oldest. Vauxhall gained over 1,400 apartments at St George Wharf across the decade from 2001 to 2012, The Tower among them at 181 metres and 49 storeys, and thousands more flats have followed along the Nine Elms and Wandsworth riverside. Most use plastic pipework buried in screed, frequently with underfloor heating, and a failure there is completely silent. It is sealed in, it spreads slowly through the screed, and the first person to notice is almost always the neighbour below.

The same construction now appears in kitchen extensions and garden rooms across Wimbledon, Richmond and Teddington, so this is not only a new build problem. Thermal imaging with the system warm shows the loops as a regular pattern and the leak as heat spreading where no loop runs, which is why under-floor detection at £300 to £700 rarely needs the floor opened to find anything.

Heat networks are part of the picture too. Lambeth Council operates 88 of them, supplying 117 buildings and more than 4,118 homes, and Clapham Park has its own network that is being expanded. On those systems there is no boiler gauge to watch, so faults on the shared plant go to the operator and only the pipework inside the flat is ours to trace.

Chalk Streams, the Tidal Thames and a Buried River

Water shapes the diagnosis here more than most people expect. Teddington Lock marks the tidal limit of the Thames, so the whole frontage from Teddington through Twickenham, Ham, Richmond and Kew is tidal, and Richmond also carries flood risk from the River Crane and Beverley Brook. In Kingston, the Hogsmill rises as a chalk stream in Ewell and meets the Thames in the town centre, and the council's flood risk work notes that most properties at risk in its catchment face river flooding rather than groundwater or surface water.

A damp basement near any of them may have nothing to do with plumbing. The survey settles that before a floor is touched: the meter is read an hour apart with nothing running, the heating pressure is checked, and if both hold steady a plumbing leak is unlikely. Moisture mapping then shows whether the pattern fits water arriving from outside, and a damp and moisture survey at £250 to £450 sets the findings out in writing.