Blocked Drain or Leaking Pipe? How to Tell Before You Call Anyone

Which Way Is the Water Going

Every wet problem in a house comes down to one of two things. Either water is failing to leave, or water is arriving where it should not. The first is a drain. The second is a pipe. They look alike on a wet floor at seven in the morning, which is why people ring the wrong trade, and why this page exists.

We are the drain people. The leak people are our sister plumbing firm, and we spend a fair amount of time sending each other’s customers back and forth. These five checks will save you the detour.

Check 1: What Does It Smell Of

Drain water smells. Even grey water from a bath or washing machine has a flat, soapy, slightly off smell, and foul water from a toilet is unmistakable. Supply pipe water is clean and smells of nothing. Heating system water smells faintly metallic or of inhibitor. If you can smell the problem, it is almost certainly ours.

Check 2: When Does It Happen

A blocked drain is worst immediately after use and after heavy rain. Flush the toilet and the bath gurgles. Run the washing machine and the gully outside fills. It rains and the manhole lifts. In between, things can look almost normal.

A leak is constant. A supply pipe is under mains pressure around the clock, so a leak on it never rests, and the wet patch is the same at midnight as at noon. A heating pipe leak follows the heating: worse when it is on, easing when it is off.

Check 3: The Meter Test

Turn off every tap and appliance in the house and make sure no toilet cistern is filling. Find the water meter, usually in a chamber under the pavement or just inside the boundary, and note the reading. Wait thirty minutes. If it has moved, water is leaving the supply pipe somewhere, and that is a leak, not a drain. If it has not moved, whatever is wet is not coming from the mains.

This single check rules a leak in or out, and our sister plumbing firm Emergency Plumbers TW offer leak detection across the TW area when it says leak.

Check 4: How Many Fixtures Are Affected

One slow sink is a local problem, usually a trap, and either trade can sort it. Two or more fixtures misbehaving at once, especially a toilet and a bath on different floors, means the shared run beneath them is blocked. That is drainage, and it needs jetting from the chamber rather than anything done at the plughole.

Check 5: Look at the Ground Outside

Lift the gully grate and the inspection chamber lid if you can. Standing water in a chamber with nothing flowing means a blockage downstream of it. A chamber running freely while the inside of the house is wet means the water is not coming from the drain at all.

On a lawn, a soft foul-smelling patch that gets worse after use is a leaking or collapsed drain. A patch that is wet, clean and constant, often with suspiciously green grass, is the supply pipe. Both are worth a camera or a listening device before anyone digs.

When It Is Both

Sometimes it is. A cracked drain lets soil and roots in, which builds the blockage, so the drain blocks repeatedly because the pipe is broken. And a drain that has backed up into the house leaves wet floors that then need the plumber’s drying kit and the insurer’s attention. The order of work is always the same: clear the drain, survey it, then deal with whatever the camera and the meter say is left.

Who to Call

• Smells, gurgles, slow fixtures, overflowing gullies, water after rain or after use: that is us. Call 07700 137648 at any hour.
• Constant wet patch, moving meter, dropping boiler pressure, water through a ceiling with the drains running fine: that is a plumber. Our sister firm answers around the clock too.

If you still cannot tell, ring either of us and describe what you can see and smell. Pointing you at the right van is part of the job, and we promise not to make it awkward.