Blocked Toilets

In short: A single blocked toilet is normally a blockage in the pan or the bend just behind it, caused by too much paper, wipes or something dropped in. A plunger often clears it. If the toilet keeps blocking, or other fittings gurgle when you flush, the problem is further down the soil pipe or drain and needs clearing properly.

A blocked toilet is one of the most stressful drainage problems because it can quickly become unpleasant, and in a house with one toilet it's urgent by default. The good news is that most toilet blockages are close to the surface and straightforward to clear.

Here's how to handle it safely, and how to tell a simple blockage from a sign of a bigger problem in the drains.

First: stop flushing

If the water in the pan is rising, don't flush again to see if it clears. Each flush adds about six litres to a bowl that can't empty, and the next one is what overflows onto the floor. If the cistern is refilling, you can lift the lid and hold the float up, or turn off the isolation valve on the supply pipe.

How to unblock a toilet yourself

A plunger made for toilets, with a flange on the bottom, works far better than a flat sink plunger. Make sure there's enough water in the bowl to cover the cup, seat it over the outlet, and push and pull firmly a dozen times without breaking the seal. If the water level drops with a gurgle, it's cleared. A coat hanger or anything sharp can scratch the glaze and catch more paper in future, so leave that out.

Why a toilet keeps blocking

A toilet that blocks every few weeks is telling you something. The common reasons are a low-flush cistern that doesn't move waste far enough down a long pipe, wipes building up at a bend or joint in the soil pipe, a partial blockage in the underground drain, or a pipe that has sagged and holds waste. If other fittings gurgle when you flush, or a downstairs shower drains slowly at the same time, the blockage is in the shared pipe rather than the toilet.

How we clear blocked toilets

We clear the pan first so it's usable again, normally with a toilet auger that passes through the bend without damaging the porcelain. If the pattern points further down, we check the soil pipe and the first manhole, and on repeat problems use a camera survey to see what's in the pipe. Removing the toilet is rarely needed.

What should and shouldn't be flushed

Only the three Ps: pee, poo and toilet paper. Wipes, cotton buds, cotton pads, sanitary products, nappies, dental floss and kitchen roll all cause blockages. Look for the Water UK "Fine to Flush" mark if you buy wipes for the toilet, and bin anything else.

Questions people ask