You step into the bathroom and your sock gets wet. There's a puddle round the bottom of the toilet, and you're not sure where it's coming from. Don't worry. Most toilet leaks come from one of four places, and you can usually find which in a few minutes.
First, stop the water
Find the isolation valve on the pipe going into the cistern. It's usually a small screw with a slot. Turn it a quarter turn with a flat screwdriver so the slot is across the pipe. No valve, or it won't turn? Use your main stopcock instead. Then dry the floor so you can see where new water appears.
Find where it's leaking from
Dry everything with a towel, flush once, and watch. Then check these four places in order:
- The water supply pipe and valve. Run dry tissue along the pipe and joints. A wet tissue means the fitting needs tightening or a new washer.
- Under the cistern. Look at the bolts that hold the cistern to the pan, and where the flush pipe meets the bowl. Drips here usually mean a worn washer or seal.
- The cistern itself. A hairline crack in the ceramic can weep slowly. Cracked cisterns need replacing, not repairing.
- The base of the toilet. If water only appears after a flush and comes from under the pan, the seal between the toilet and the waste pipe has failed. This is the one to take seriously.
Is the toilet leaking into the bowl instead?
If there's no water on the floor but you can hear a trickle into the bowl, that's a different problem. Read our guide on a toilet that keeps running.
Why a leak at the base matters
Water from the waste seal is dirty water. It soaks into floorboards, can rot them, and in a flat it often drips through the ceiling below. If you live above someone, a leak at the base of the toilet is worth fixing the same day.
Quick fixes you can try
- Tighten a dripping compression nut on the supply pipe by a quarter turn. Don't overdo it.
- Check that the toilet doesn't rock. A loose pan can break its seal. Fixing screws at the base may just need tightening.
- Replace a damp flexible connector. They're cheap and screw on by hand.
When to call us
Call a plumber if the leak comes from the base of the toilet, the cistern is cracked, the isolation valve won't turn, or water is coming through a ceiling. We'll find the cause, fix it, and check the floor for damage.
Common questions
Why is my toilet leaking from the bottom?
Usually the seal between the toilet and the waste pipe has failed, or water is dripping down from the cistern bolts or supply pipe. Dry everything and flush to see where it starts.
Is a leaking toilet an emergency?
A leak at the base can soak floorboards and come through the ceiling below, so fix it the same day. Turn off the isolation valve and avoid flushing until then.
How do I stop my toilet cistern leaking?
Turn off the isolation valve and check the bolts and washers under the cistern. Worn washers can be replaced. A cracked cistern needs replacing.
Can I still use a leaking toilet?
If the leak comes from the base, try not to. Every flush pushes dirty water under the floor. If it's only the supply pipe, turn the water off between uses.