A toilet that keeps running is easy to ignore until the water bill arrives. A constant trickle can waste a surprising amount of water every day. The good news is that you can usually fix a running toilet with a part that costs less than a lunch. No plumber required.
How a Toilet Tank Works
Take the lid off the tank and look inside. You’ll see two main parts. The fill valve on the left refills the tank after each flush, and the flapper at the bottom lets water drop into the bowl. A running toilet almost always comes down to one of these two.
Find Out Why Your Toilet Keeps Running
Try this quick test. Look at the overflow tube in the middle of the tank.
- If water is spilling into the overflow tube, the water level is too high. The fill valve or float needs adjusting.
- If the water is below the tube but the toilet still runs, the flapper is probably leaking.
To confirm a leaky flapper, add a few drops of food coloring to the tank. Wait 15 minutes without flushing. If color shows up in the bowl, the flapper isn’t sealing.
Adjust the Float to Lower the Water Level
Most modern fill valves have a float cup that slides on the valve shaft. Turn the adjustment screw or pinch the clip and slide the float down about half an inch. Older toilets use a float ball on an arm. Bend the arm down slightly or turn its adjustment screw.
The water should stop about one inch below the top of the overflow tube. Flush and check again.
How to Replace a Toilet Flapper
A warped or worn flapper is the most common cause of a running toilet. Here’s how to swap it:
- Turn off the water at the shut-off valve behind the toilet.
- Flush to drain the tank.
- Unhook the chain from the handle lever and pop the flapper ears off the pegs on the overflow tube.
- Take the old flapper to the store so you can match the size (most are 2 or 3 inches).
- Clip on the new flapper and attach the chain with about half an inch of slack.
Turn the water back on and test a few flushes. A chain that’s too tight will hold the flapper open. Too loose, and it can get caught underneath.
Clean the Flush Valve Seat
Before you install the new flapper, run your finger around the rim it sits on. Mineral buildup there can stop even a new flapper from sealing. Scrub it gently with a scouring pad.
When to Replace the Fill Valve
If the fill valve hisses, refills slowly or won’t shut off even after adjusting the float, replace it. Universal fill valve kits come with clear instructions. Shut off the water, drain the tank, unscrew the supply line and the locking nut under the tank, and swap in the new valve. The whole job takes about 30 minutes.
Tips to Keep Your Toilet Working Well
- Avoid drop-in tank cleaning tablets. They can wear out rubber parts faster.
- Check the tank once or twice a year for slow leaks.
- Keep a spare flapper in your toolbox. It’s cheap insurance.
More Easy Plumbing Fixes
Once the toilet is quiet, look for other small leaks around the house. Our guide on how to fix a leaky faucet covers the next most common water waster. You might also want to replace your showerhead or learn how to reset a garbage disposal. New to plumbing tools? Start with our essential DIY tool kit for beginners.
