GPS-referenced drainage mapping surveys for London properties — accurate drain layout plans showing pipe routes, invert levels, flow directions, and manhole positions. Required for extensions, build-over applications, and estate or leaseholder drainage records.
Free, no-obligation — we'll call you back fast.
A drainage mapping survey combines a CCTV camera inspection with GPS positioning to produce an accurate plan of your property's drainage layout — showing where each pipe runs, the direction of flow, invert levels at each manhole, and the relationship between private and public sewer connections. In London, accurate drainage plans are essential for any extension or basement conversion built close to an existing drain run, because Thames Water requires evidence that the work does not affect the structural integrity of the public sewer. Furthermore, many older London properties have no drainage records at all — the Victorian-era pipes were never formally documented — so a mapping survey is often the only way to establish the layout before design work begins. In addition to building projects, drainage mapping surveys are frequently required by managing agents and freeholders for blocks of flats, HMOs, and converted Victorian terraces where responsibility for shared drainage is disputed between leaseholders. Therefore, a single mapping survey conducted by a neutral party produces the definitive record that all parties can rely on. As a result, disagreements about drainage responsibility — which can otherwise run for months through solicitors — are typically resolved within days of the mapping report being issued. We produce drainage plans in a clear format suitable for submission to architects, structural engineers, Thames Water, and local planning authorities.
Identify all accessible drain entry points — manholes, inspection chambers, rodding eyes
CCTV camera survey to trace all drain runs and confirm flow directions
GPS coordinate capture at each manhole and direction change
Invert level measurement at each accessible chamber
Drainage layout plan produced showing all pipe routes, sizes, flow directions, invert levels, and connection points
Drainage mapping surveys for London residential properties are priced according to the complexity of the drainage network, the number of manholes, and the level of detail required in the output plan. Commercial and estate mapping surveys are quoted individually. Request a fast, fixed-price quote online.
Yes. Thames Water requires a pre-build CCTV drain survey confirming the condition of the public sewer before approving a build-over agreement for any extension or structure within 3 metres of an adopted sewer. A drainage mapping survey provides this evidence and also produces the plan showing the sewer position relative to your proposed structure that Thames Water typically requires alongside the condition report.
A mapping survey combined with a Thames Water drainage search can establish which sections of your drainage network are privately owned (your responsibility) and which are adopted public sewers (Thames Water's responsibility). This is particularly important in London's converted Victorian terraces and blocks of flats where drainage ownership is often unclear.
A standard residential drainage mapping survey takes 1–3 hours on site, depending on the size and complexity of the network. The mapping plan is typically delivered within 48 hours of the survey. For complex estates or commercial properties requiring multiple manhole runs, allow 2–5 days for the completed plan.