There is nothing quite as annoying as the constant, hissing sound of a toilet that just won't stop running after you flush it. Not only is the noise maddening, but a running toilet can waste hundreds of gallons of water a day, causing a massive spike in your monthly utility bill.
Before you call a plumber to charge you $150 for a 5-minute job, take the lid off the back of your toilet tank. A running toilet is almost always caused by one of three cheap plastic parts inside the tank that you can easily adjust or replace yourself.
Here is how to diagnose the issue and silence your toilet for good.
1. Check the Flapper and Chain (The 15-Second Fix)
The flapper is the rubber seal at the very bottom of the tank that lifts when you flush and drops back down to hold the water in. If it doesn't seal perfectly, water constantly leaks into the bowl, forcing the toilet to keep refilling.
- The Fix: Look at the metal or plastic chain connecting the flush handle lever to the rubber flapper. If the chain is too short, it holds the flapper open. If it is too long, it can get trapped underneath the flapper. Adjust the clip on the chain so it has just a tiny bit of slack (about half an inch).
- The Flapper Test: Reach in and press down lightly on the rubber flapper with your finger. If the running sound immediately stops, your flapper is old, warped, or coated in mineral buildup. You can buy a universal Korky or Fluidmaster replacement flapper for about $5 and snap it on in seconds.
2. Lower the Float (The Water Level Fix)
Inside the tank, there is an overflow tube (an open pipe in the middle). If the water level rises higher than that tube, it will constantly spill down into the bowl. The water level is controlled by the "float."
- The Fix (Older Toilets): If you have an older toilet with a big rubber ball on the end of a metal arm, simply grab the metal arm and bend it slightly downwards. This tells the water to shut off sooner.
- The Fix (Modern Toilets): Modern toilets use a tall plastic fill valve with a float cup that slides up and down the shaft. Look for a long plastic screw attached to the float. Take a Phillips-head screwdriver and turn the screw counter-clockwise. This lowers the float and drops the water level safely below the overflow tube.
3. Replace the Fill Valve
If you adjusted the float, but water is still spraying aggressively from the top of the tall plastic tower on the left side of your tank, the internal seals on your fill valve have failed.
- The Fix: Don't be intimidated by this! You can buy a complete universal fill valve replacement kit for under $15. Turn off the water supply valve on the wall behind the toilet, flush the toilet to empty the tank, and use a sponge to soak up the remaining water. Then, simply unscrew the water line from the bottom of the tank outside, pop the old valve out, and drop the new one in.
When to Call a Pro
If you have replaced the flapper and the fill valve, and you notice water pooling on your bathroom floor around the base of the toilet, the wax ring underneath the entire toilet unit has failed. While you can replace a wax ring yourself, it requires physically unbolting and lifting the heavy porcelain toilet off the floor. If you aren't comfortable with heavy lifting, this is the time to call a professional.