You can repair a running toilet yourself by checking four parts in the same order every time: the flapper, the chain, the water level and the fill valve. Most of the time the flapper is worn or the chain is snagged, and replacing a flapper takes about as long as a cup of coffee. This page covers each step, the odd cases (random refills, Kohler canister models, a slow tank), and the point where a local plumber is the better call. If the problem is wider than the tank, our Toilets page lists the Toilet Repair Services we can arrange, from a single part to a full replacement.
How do you repair a running toilet?
Turn off the water at the small valve on the wall behind the toilet, lift the tank lid, and work through four checks: flapper seal, chain slack, water level against the overflow tube, then the fill valve. Replace the first part that fails. A worn flapper is the usual culprit, and it is the cheapest part to swap.
Do the checks in this order because each one is quicker than the next. Flush once with the water on so you can watch the parts move, then look.
- Flapper. The rubber seal (our toilet flapper repair guide goes deeper) at the bottom of the tank should drop flat over the drain opening. If it is curled, cracked, slimy or hard, replace it with one that matches your toilet. Take the old one to the store.
- Chain. There should be a little slack, about the width of a thumb. Too tight and it holds the flapper open a crack. Too loose and it can slip under the flapper and keep it from seating.
- Water level. The tank should fill to the waterline marked inside it, and no higher than about an inch below the top of the overflow tube. Higher than that and water spills down the tube all day.
- Fill valve. If the level is right but the valve hisses and will not shut off, clean its seat or follow our guide to repairing a toilet fill valve.
How do you tell which part is making the toilet run?
Add a few drops of food coloring to the tank and wait ten minutes without flushing. If color shows up in the bowl, the flapper is leaking. If the bowl stays clear but you hear the tank refilling, water is probably escaping down the overflow tube because the level is too high or the fill valve is failing.
That dye test comes from the EPA's WaterSense program, and it is the fastest way to stop guessing. Flush when you finish so the dye does not stain the tank.
A second quick check: look at where the water sits. If it is touching the overflow tube opening, the fill valve is the cause. If it sits well below the tube but the toilet keeps topping off, the flapper is letting water seep into the bowl. Both can be true at once, which is why replacing a flapper and then testing again is a normal sequence rather than a failure.
How do you fix a toilet that runs constantly?
A toilet running without pause is either leaking past the flapper or overfilling into the overflow tube. Replace the flapper first, then lower the float or adjust the fill valve so the water stops about an inch below the tube. If it still runs, replace the whole fill valve, which is a standard part.
A constant sound of running water is the worst case for your bill. The EPA says a leaking toilet can waste about 200 gallons a day, and a stuck fill valve can pass far more than that. Shut the angle stop while you work, and do not leave a constantly running toilet for a week.
To lower the level on a float cup fill valve, turn the adjustment screw or slide the clip down the rod. On an older ball-and-arm ballcock, bend the arm gently downward. If the water will not stay below the tube whatever you do, the valve itself is spent.
Why does a toilet run randomly or every few minutes?
A toilet that refills by itself every few minutes, or runs for a while and stops, has a slow leak. The flapper lets a little water seep into the bowl, the tank level drops, and the fill valve tops it up. The dye test finds it. Replace the flapper and clean the seat it sits on.
People call this a ghost flush or a phantom flush. It can also be intermittent for a different reason: a fill valve that sticks now and then, or a chain that only snags on some flushes. When it happens a few times an hour, treat it exactly like a constant run. The cause is the same, it just shows up more slowly.
Here in Los Angeles, hard water makes this more likely. LADWP counts water above 7 grains per gallon as hard, and its 2022 averages ran from about 8.6 grains in the Valley and West Los Angeles to 16.3 in the east and the harbor area. Mineral scale roughens the flapper seat, so a brand new flapper can still leak. Wipe the seat with a damp cloth or a non-scratch pad before you fit the new one.
How do you fix a running Kohler toilet?
Many Kohler toilets use a canister flush valve, not a rubber flapper. If the toilet runs on and off, the seal at the base of the canister is usually worn or dirty. Clean the seal and its seat, check that the canister sits straight, and replace the seal with the Kohler part for your model if it is cracked.
Kohler's own troubleshooting guide covers the same water-level rule: adjust the fill valve so the water reaches the marked waterline and no higher. It also says to clean debris off the fill valve seat, or replace the valve if its float sinks or the level climbs above the top of the canister. Vinegar and water will dissolve mineral buildup on a canister that sticks.
Match parts to the model number stamped inside the tank. Canister seals and flappers are not interchangeable across brands, and a universal part that nearly fits is a common reason the running comes back.
What if the toilet bowl keeps running or the tank fills slowly?
Water moving in the bowl without a flush points to the same flapper leak. A tank that fills very slowly is a different fault: the supply is restricted. Open the wall valve fully, check the supply line for kinks, and clean the fill valve filter. If the angle stop itself is stiff or leaking, replace it.
Slow filling feels like running because the valve stays open longer, and it can make a toilet sound as though it is still running a minute after the flush. Debris in a fill valve, a half-closed angle stop and mineral buildup in the supply line are the three usual reasons. A shut-off valve that has not been turned in years can crumble when you try it, so go gently. If it will not close fully, that is a plumber's job and a good time to replace it.
How much does a running toilet cost you in Los Angeles?
A running toilet can waste up to roughly 200 gallons a day according to the EPA, which shows on a water bill within a billing cycle. Even a small flapper leak can waste around 30 gallons a day. The repair parts cost a small fraction of what that water costs over a few months.
If your toilet is an older 1.6 gallon model or worse, repair may not be the best spend. LADWP's residential SoCal Water$mart page lists a $250 rebate for replacing a 1.6 gallons-per-flush toilet or larger with one that uses 1.1 gallons or less, and you apply with a recent bill and a receipt. Check the current terms before you buy, since rebate funds and rules change.
California's Civil Code also requires older single-family homes to have water-conserving fixtures, with toilets limited to 1.6 gallons per flush. If yours is older than that limit, replacing it solves the running and the compliance question together.
When should you call a plumber for a running toilet?
Call a plumber if you have replaced the flapper and fill valve and the toilet still runs, if the water shut-off valve will not close, if water is leaking from the base or the tank bolts, or if you cannot find the part number for an older toilet. Tank bolt and gasket leaks mean lifting the tank off the bowl.
We can arrange a local plumber to come to your home, look at the whole fixture and give you a written quote before any work starts. Send the details on our quote page and say what you have already tried, so the visit starts at the real problem. For a general read on how a job runs, see how a job runs.
The repair is not always urgent, but a constant run is worth stopping the same day. You will thank yourself when the next bill arrives. Most people never need more than a flapper, so do the dye test first and spend the money only where the test points. You can also come back to our home page to see the other plumbing jobs we can arrange.
Common questions
How long does it take to repair a running toilet?
Most running toilets take 15 to 30 minutes to fix when the cause is the flapper, chain or water level. Replacing a fill valve takes closer to an hour the first time, because you have to drain the tank, disconnect the supply line and tighten the new valve without cracking the tank. Allow extra time if the shut-off valve is stuck.
Can I use a universal flapper?
You can, but match it to the flush valve size, usually 2 inch or 3 inch, and check the fit. A universal flapper that does not sit flat will leak just like a worn one. On Kohler canister toilets there is no flapper at all, so you need the canister seal made for that model.
Why does my toilet run again after I fix it?
The usual reasons are scale on the flapper seat, a chain that still catches, a water level set too high, or a fill valve that was damaged when you tightened it. Wipe the seat clean, give the chain a thumb of slack, and test with dye again. If it still runs, the fill valve is the next part to replace.
Is a running toilet dangerous?
It is not dangerous, but it is wasteful, and it can mean an overflow if the fill valve fails completely. If the water starts rising toward the rim, turn the angle stop on the wall clockwise to shut it off. A toilet that runs and also leaks onto the floor can damage a subfloor, so deal with that one quickly.
Do I need a permit to repair a toilet in Los Angeles?
Swapping a flapper, fill valve or canister seal is generally treated as routine maintenance, not permit work. Replacing the toilet itself or moving plumbing can be different, so ask the plumber who quotes the job. Where a permit applies, a plumber with a California contractor license normally handles it.