Why Is My Toilet Running?
That constant hissing or trickling sound from your toilet isn't just annoying — it's expensive. A running toilet typically wastes a significant amount of water every day it goes unfixed. The good news: in the vast majority of cases, the fix costs under $20 and takes less than an hour. No plumber required.
What You'll Need
- Adjustable wrench or pliers
- Replacement flapper (available at any hardware store — bring your old one to match)
- Replacement fill valve (optional, if the flapper isn't the issue)
- Paper towels or a sponge
Step 1: Identify the Cause
Remove the toilet tank lid and set it safely aside. Observe what's happening inside. There are three main culprits:
- Faulty flapper: The rubber seal at the bottom of the tank isn't closing properly. Water seeps into the bowl continuously.
- Float set too high: Water rises above the overflow tube and drains away constantly.
- Faulty fill valve: The valve that refills the tank after flushing won't shut off.
Quick test: Add a few drops of food coloring to the tank. Wait 10 minutes without flushing. If color appears in the bowl, your flapper is leaking.
Step 2: Fix a Faulty Flapper
This is the most common fix and takes about 10 minutes.
- Turn off the water supply valve behind the toilet (turn clockwise).
- Flush the toilet to empty the tank.
- Unhook the flapper chain from the flush handle arm.
- Slide the old flapper off the pegs on either side of the overflow tube.
- Slide the new flapper onto the same pegs and reconnect the chain. Leave about ½ inch of slack in the chain.
- Turn the water supply back on and let the tank fill.
- Test the flush and check for leaks.
Step 3: Adjust the Float
If the water level is above the top of the overflow tube, it will drain constantly.
- Ball float (older style): Bend the float arm slightly downward, or turn the adjustment screw at the base of the arm to lower the water level.
- Cup float (modern style): Pinch the clip on the side of the fill valve and slide the float down. The water level should sit about 1 inch below the top of the overflow tube.
Step 4: Replace the Fill Valve
If the tank still runs after fixing the flapper and float, the fill valve likely needs replacing. This takes about 20 minutes.
- Turn off the water supply and flush to empty the tank.
- Use a sponge to remove any remaining water.
- Disconnect the water supply line from the bottom of the tank.
- Unscrew the locknut underneath the tank holding the fill valve in place.
- Pull out the old valve and insert the new one. Adjust its height per the package instructions.
- Tighten the locknut, reconnect the supply line, and turn the water back on.
- Adjust the float on the new valve so water stops 1 inch below the overflow tube.
When to Call a Plumber
DIY fixes cover the vast majority of running toilet issues. Call a plumber if:
- You notice cracks in the tank or bowl.
- The toilet rocks or there's water on the floor around the base.
- You've replaced the flapper and fill valve but the problem persists.
Cost Comparison
| Repair | DIY Cost | Plumber Cost |
|---|---|---|
| Replace flapper | $5–$10 | $75–$150 |
| Replace fill valve | $10–$20 | $100–$200 |
| Adjust float | Free | $75+ |