That faint hissing, the trickle that never quite stops, the toilet that seems to refill itself in the middle of the night. A running toilet is one of the most common household plumbing annoyances, and one of the most wasteful. A toilet that leaks even a small amount continuously can waste hundreds of gallons of water over a day or more, and the cost shows up on your water bill. The good news is that most running toilets can be fixed in under an hour with parts that cost a few dollars.
How a toilet works, briefly
A toilet tank holds water behind the bowl. When you flush, a rubber flapper at the bottom of the tank lifts, and water rushes into the bowl. The flapper then drops back down to seal the opening, and a fill valve refills the tank until a float tells it to stop. If the flapper does not seal, the fill valve, the float or the overflow tube is not working properly, water keeps moving, and the toilet runs.
Do a quick diagnosis
Start with these checks:
- Listen and look. Remove the tank lid and set it down carefully, since it is porcelain and heavy. Flush and watch what happens.
- Check the water level. The water should stop about one inch below the top of the overflow tube, the vertical pipe in the center. If water is spilling into the tube, the fill valve or float is set too high or is failing.
- Do the dye test. Put a few drops of food coloring or a dye tablet in the tank. Do not flush. Wait 15 to 30 minutes. If color appears in the bowl, the flapper is leaking.
- Check the chain. If the chain is too tight, it keeps the flapper from closing. If it is too loose, it can get caught under the flapper.
Fix 1: Adjust or replace the flapper
The flapper is the most common culprit. Over time, rubber warps, hardens or collects mineral deposits and no longer seals. First, turn off the water at the shutoff valve behind the toilet, and flush to empty the tank. Wipe the flapper and the seat clean, since sometimes grime is the only problem. If the flapper looks worn or misshapen, replace it. Take the old one to the hardware store to match the size and style, or buy a universal flapper. Attach it to the pegs on the overflow tube, connect the chain with a small amount of slack, about half an inch, and turn the water back on.
Fix 2: Adjust the float
If the water level is too high, adjust the float. On older ball-style floats, gently bend the arm down or turn the adjustment screw. On cup-style floats, there is usually a screw or clip on the rod that you slide to lower the cup. Adjust a little at a time until the water stops about an inch below the overflow tube.
Fix 3: Replace the fill valve
If the tank keeps filling even when the level is correct, or the valve hisses constantly, it may be worn out. Replacement kits are inexpensive and generally universal. Turn off the water, flush, disconnect the supply line, remove the old valve and install the new one according to the instructions. Adjust the height as directed, reconnect the line and test it.
Fix 4: Check the overflow tube and seat
A cracked overflow tube or a rough flapper seat can also cause a leak. Light mineral buildup on the seat can be cleaned with a non-abrasive scrub pad. If the seat is damaged, consider a repair kit or professional help.
Phantom flushing
If the toilet refills by itself every so often, even when no one has flushed, it is usually a slow leak past the flapper. The dye test will confirm it.
Cost and time
Most parts, such as flappers and fill valves, cost relatively little, and the repair takes less than an hour. A plumber may charge a minimum service fee, so a DIY fix can save money for a simple problem. If you are not comfortable, or if the toilet has other issues such as a cracked tank or loose base, call a plumber.
Check your water bill
If your bill jumps unexpectedly, a running toilet is a prime suspect. Some water utilities offer leak adjustment programs that reduce charges after a documented leak is repaired, so ask your provider. You can also check your water meter. With all taps and appliances off, if the meter is still moving, you have a leak.
Renters: who pays and who fixes
In most rentals, the landlord is responsible for maintaining plumbing fixtures in good working order, though some leases assign minor repairs to tenants. Report a running toilet promptly and in writing. Delaying can lead to disputes over whose responsibility the extra water bill is, and neglect that causes damage may be blamed on the tenant. If your lease makes you pay for water, you have a particularly good reason to report and fix the problem quickly. Ask permission before replacing parts yourself, and keep receipts.
Keep it healthy
When you clean your bathroom, take a quick look at the tank. Replace the flapper every few years as a preventive measure, and check for leaks regularly.