How do I fix a running toilet?
Short answer: A running toilet usually has one of two problems. Water spills into the overflow tube because the water level is set too high, or a worn flapper leaks water into the bowl. Do a food-coloring dye test, then lower the water level to the tank's fill mark (often about 1 inch below the overflow tube) or replace the flapper. EPA says a running toilet can waste 200 gallons or more per day.
How much water does a running toilet waste?
A toilet that runs nonstop can waste 200 gallons of water or more every day, according to an EPA WaterSense fact sheet. A slow, silent leak wastes less, but EPA says a worn flapper can still leak thousands of gallons a year. EPA names old or worn-out flappers as a common cause of toilet leaks, and they are cheap to replace.
How do I know if my toilet is leaking?
Silent leaks are common. Use EPA’s dye test to find them (EPA says to wait 10 minutes):
- Remove the tank lid.
- Add a few drops of food coloring to the tank water. Do not flush.
- Wait 10 minutes.
- If color shows up in the bowl, water is leaking from the tank past the flapper.
- Flush right away so the dye does not stain the tank.
How does a toilet tank work?
These parts do most of the work:
| Part | What it does |
|---|---|
| Flapper | Rubber seal at the bottom of the tank. It lifts when you flush and drops to seal the drain hole. |
| Chain | Connects the flush handle arm to the flapper. |
| Fill valve | Tall valve on the left side. It refills the tank after a flush. |
| Float | A cup or ball on the fill valve. As water rises, the float rises and shuts the valve off. |
| Overflow tube | Open pipe in the center. It sends excess water into the bowl so the tank cannot flood. |
A running toilet means water is escaping somewhere. It is either going over the overflow tube or under the flapper.
Why does my toilet keep running? Find the cause
Take the lid off and watch the tank after it refills.
Before any repair, shut off the supply valve behind the toilet. If that valve is stuck or leaking, stop and call a plumber.
| What you see | Likely cause | Fix |
|---|---|---|
| Water flows into the top of the overflow tube | Water level set too high, or fill valve will not shut off | Lower the float. Replace the fill valve if that fails. |
| Water level is below the tube, but tank refills on its own | Flapper leaks | Clean or replace the flapper |
| Dye test shows color in the bowl | Flapper leaks | Clean or replace the flapper |
| Toilet runs until you jiggle the handle | Chain too short, tangled, or caught | Adjust the chain |
How do I adjust the water level?
Many tanks have a water line marked inside. If yours does, follow that mark. If not, a common target is about 1 inch below the top of the overflow tube; check your toilet or fill valve instructions.
- Float cup (most modern valves): Turn the adjustment screw or squeeze the clip and slide the cup down.
- Float ball on an arm (older valves): Turn the adjustment screw on top of the valve. Some metal arms can be bent down gently; do not bend plastic arms.
Flush and check the new level. If water still rises into the overflow tube after adjusting, the fill valve may be worn. Replace it.
How do I fix a leaking flapper?
- Turn off the water supply valve behind the toilet (turn clockwise).
- Flush to drain the tank.
- Check the flapper and the drain seat for grime or mineral buildup. Wipe both clean.
- If the rubber is warped, stiff, or cracked, replace it.
Flappers come in 2-inch and 3-inch sizes. Measure the drain opening, or bring the old flapper to the store. A mismatched flapper will keep leaking. To install, unhook the old one from the pegs on the overflow tube and hook on the new one.
Set the chain length. Leave a little slack, about half an inch, with the flapper closed. Too tight, and the flapper cannot seal. Too loose, and the chain can get trapped under the flapper or give a weak flush. Trim extra chain so it cannot tangle.
Do the dye test again after the repair.
How do I replace a fill valve?
- Shut off the water at the supply valve behind the toilet.
- Flush and hold the handle down to drain the tank.
- Sponge out the water left in the tank. Keep a towel and bucket under the tank.
- Disconnect the supply line from the bottom of the tank.
- Remove the old valve. Unscrew the lock nut under the tank and lift the valve out.
- Set the new valve height. Most universal valves adjust. Follow the maker’s instructions and height mark (often labeled CL, for critical level) relative to the overflow tube.
- Install and tighten the lock nut hand-tight plus a small turn. Overtightening can crack a porcelain tank.
- Clip the refill tube to the overflow tube as the instructions show. Do not push it down into the tube.
- Reconnect the supply line, turn the water on slowly, and check for drips.
- Set the water level at the tank’s mark, or as the valve instructions direct (often about 1 inch below the top of the overflow tube).
What does a running toilet cost?
The formula:
Cost = gallons per day × days ÷ 1,000 × price per 1,000 gallons
Water and sewer prices vary widely by city. Many US utilities bill sewer based on water use, so use your combined rate if yours does. Check your bill for it. The table shows a running toilet (200 gallons/day, EPA) and a slower, illustrative 30 gallons/day leak.
| Combined price per 1,000 gal | 30 gal/day, per month | 30 gal/day, per year | 200 gal/day, per month | 200 gal/day, per year |
|---|---|---|---|---|
| $5 | $4.50 | $54.75 | $30 | $365 |
| $10 | $9 | $109.50 | $60 | $730 |
| $15 | $13.50 | $164.25 | $90 | $1,095 |
| $20 | $18 | $219 | $120 | $1,460 |
Example at $10 per 1,000 gallons: 200 × 30 ÷ 1,000 × $10 = $60 a month.
When should I call a plumber?
Call a plumber if:
- Water leaks onto the floor from the base, tank bolts, or supply line after you have tightened them.
- The tank or bowl is cracked.
- The shutoff valve behind the toilet will not turn or leaks itself.
- The toilet still runs after you replace both the flapper and the fill valve.
Quick answers
Why does my toilet run every few minutes? This is often called “phantom flushing.” Water slowly leaks past the flapper, so the tank refills. Clean or replace the flapper.
How do I know if my flapper is 2-inch or 3-inch? Measure the drain opening at the bottom of the tank. Or remove the old flapper and compare it to the packages at the store.
How high should the water be in a toilet tank? At the water line marked inside the tank. Without a mark, about 1 inch below the top of the overflow tube is a common target.
How much does a running toilet raise my water bill? At 200 gallons a day and $10 per 1,000 gallons, about $60 a month. Use the table above with your own rate.