A leaking toilet usually leaks from one of four places: the pan connector where the toilet meets the soil pipe, the joints between the cistern and the pan, the water supply pipe and valve, or internally from the cistern into the bowl. The first three put water on the floor; the fourth just keeps the bowl running. Finding the exact point matters because each has a different fix, and some that look like a leak are actually condensation. Start with the simple checks below before anything is taken apart.
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First, dry everything and watch
Wipe the floor, the pan, the cistern and the pipes completely dry. Lay some dry kitchen roll around the base. Then flush once and watch. The first place that gets wet is usually the source, because water runs down and along, and the puddle on the floor is often a long way from the actual leak.
Leak 1: at the back of the pan
If water appears at the back after flushing, the pan connector into the soil pipe is the likely cause. These rubber or plastic connectors perish with age, or pull apart if the pan has moved. Replacing the connector means taking the pan off, so it is also a good moment to check the floor fixings. A pan that rocks will break a new seal in the same way, which our wobbly toilet guide covers.
Leak 2: between cistern and pan
On close coupled toilets, the cistern bolts onto the back of the pan with a large doughnut washer and two or three bolts with their own washers. If water drips from underneath the cistern after a flush, one of these has failed. Tightening the bolts gently can help briefly, but overtightening can crack the ceramic. The proper fix is new washers, which means draining and lifting the cistern.
Leak 3: the supply pipe and valve
Water that is there all the time, not just after flushing, often comes from the feed pipe, the isolation valve or the fill valve connection under the cistern. Run a dry tissue around each joint. A compression joint may just need a small nip; an isolation valve weeping from the spindle may need replacing.
Leak 4: water running into the bowl
If you can hear the cistern filling every so often without anyone using it, or see a ripple down the back of the bowl, water is getting past the flush valve seal or overflowing from a fill valve that is set too high. It is not a floor leak, but it wastes a lot of water. A few drops of food colouring in the cistern will show up in the bowl within half an hour if the seal has failed. Our guide to a toilet not flushing properly explains the parts involved.
Not a leak: condensation
In cold weather, a cistern filled with cold mains water sweats in a warm, steamy bathroom. The droplets run down and gather at the base, looking exactly like a leak. Better ventilation is the answer; see our ventilation guide.
Damage to check for
A leak that has gone on for a while can soften the floorboards around the pan and stain the ceiling underneath. If the floor feels spongy, it has to be repaired before the toilet is refitted, or the new seals will fail as the pan moves.
Repair or replace?
Most leaks are fixed with new seals and connectors. If the pan or cistern is cracked, or the parts for an old cistern are no longer made, a new toilet is the sensible fix; our toilet replacement guide explains what that involves.
Getting a leak fixed
Leak diagnosis and toilet repairs are part of our bathroom repairs service, done by our own plumbers. Tell us where the water is showing or call 01782 901390.
Common questions
Why is there water around the base of my toilet?
The most common causes are a failed pan connector to the soil pipe, a leaking supply joint dripping down, or condensation on the cistern running down in cold weather. A pan that rocks can also break the connector seal.
How can I tell if it is condensation?
Dry everything, then check the outside of the cistern and pipes. If they are covered in beads of water all over, especially in winter, it is condensation. A leak usually starts from one point.
Is it a leak if water keeps running into the bowl?
That is an internal leak. The flush valve seal or fill valve is letting water pass constantly. It wastes water but does not wet the floor.
Is a leaking toilet urgent?
Water from the base or connector should be dealt with quickly because it can soak the floor and ceiling below, and waste water is unhygienic. An internal leak into the bowl is less urgent but wastes water.