Drain Odour Investigation in Nelson , Lancashire

That rotten egg smell is hydrogen sulphide escaping from sewer pipes into your living space. In Clayton-Le-Moors, we usually trace this back to a dried-out water trap under a spare bath, a degraded seal behind a toilet, or a split soil stack pipe boxed in behind a wall. If waste water is flowing away without backing up, sewer gas is escaping through an air breach rather than a standard blockage.

We use smoke testing equipment to inject dense, non-toxic smoke under light pressure straight into the drainage run. Any hairline crack, loose mechanical fitting, or faulty air admittance valve will immediately leak visible smoke right at the exact source of the odour. It lets us pinpoint the problem fast without tearing down plasterboard or lifting floorboards on guesswork.

A camera cannot see air or gas, but it spots the physical defects that let foul air travel where it should not. We use CCTV cameras to look for cracked clay pipes, displaced pipe joints, dried-out interceptor traps, or uncapped redundant pipe runs. Once we identify where the pipework is broken or unsealed, we know precisely how the bad air is getting into the building structure.

Yes, this is very common in older stone and brick terraced houses where shared clay drains run beneath or behind the buildings. Rats often chew through plastic soil pipes, push past faulty rubber flap valves, or tunnel out of broken sub-floor lines, leaving open holes that let sewer gas vent under your floor. If the odour smells sharply of ammonia or rotting organic matter alongside normal sewer smells, rodent damage in the drainage is usually the cause.

Run a litre of water down every sink, shower, washing machine standpipe, and bath trap in the house to make sure none of the water seals have dried out. If you have an internal air admittance valve (Durgo valve) fitted in a loft space or under a sink, check that its rubber diaphragm has not perished or jammed open. If all the traps are full of water and the smell persists, you have an unsealed air leak in the pipework that needs testing.

Sewer air contains toxic gases like methane and hydrogen sulphide, which can cause headaches, eye irritation, and nausea if you are breathing them in continuously. UK Building Regulations Part H requires all indoor drainage to maintain an airtight barrier precisely to protect living spaces from these fumes and airborne bacteria. You should not just mask the smell with room sprays, because a sewer smell always points to a broken seal or pipe that needs sealing properly.