Stop a Running Toilet

Water running constantly in a toilet tank isn't just annoying—it's expensive. A single running toilet wastes 200 gallons per day, adding $50 to $100 to your annual water bill for absolutely nothing. The sound is maddening at night, and the knowledge that money is literally flowing down the drain makes it worse. The good news: nearly every running toilet comes down to three cheap parts in the tank, and you can fix any of them in an hour without calling anyone. You'll turn off one valve, swap out a component or two, and restore silence. The tank mechanism looks mysterious until you spend five minutes looking at it, then it's obvious. This is one of those repairs where doing it yourself isn't just cheaper—it's genuinely faster than waiting for a plumber.

1. Spot the Real Problem. Remove the tank lid and flush while watching what happens. If water keeps trickling into the bowl after the tank refills, the flapper isn't sealing. If the fill valve keeps running and water spills into the overflow tube, the float is set too high. If you hear periodic hissing, check the refill tube. Mark which issue you're seeing before you buy parts.
2. Cut the Water Off. Turn the oval shutoff valve clockwise until it stops—it's on the wall or floor behind the toilet, where the supply line connects. Flush once to drain the tank. Use a sponge to soak up the remaining inch of water in the bottom. You want the tank empty and dry for the repair.
3. Swap the Flapper Out. Unhook the old flapper from the pegs on either side of the flush valve and disconnect the chain from the flush lever. Slide the new flapper onto those same pegs and attach the chain with about half an inch of slack when the flapper is seated. The flapper is the rubber seal at the bottom of the tank—when it hardens or warps, water seeps past it constantly.
4. Fine-Tune the Fill Valve. If water runs into the overflow tube, pinch the adjustment clip on the fill valve and slide the float down one inch. Test by turning water back on briefly. If adjustment doesn't fix it, unscrew the fill valve locknut under the tank, pull out the old valve, and install the new one at the height marked on the instructions. The fill valve should shut off when water sits one inch below the overflow tube.
5. Reposition the Refill Tube. The small vinyl tube that clips onto the overflow pipe should hang just inside the pipe opening, not down inside it. If it's pushed too far down or disconnected, the fill valve can't sense when to shut off. Clip it securely to the top edge of the overflow tube with the angle clip provided.
6. Balance the Chain Slack. The chain connecting the flush lever to the flapper needs just enough slack that the flapper seals completely, but not so much that it gets caught under the flapper. With the flapper closed, you should see about half an inch of loose chain. Adjust by moving the chain connection to a different hole in the lever arm.
7. Run a Full Test Cycle. Open the shutoff valve slowly and let the tank fill completely. Watch to confirm the fill valve shuts off cleanly with water about an inch below the overflow tube. Flush and observe a full cycle—the flapper should drop and seal immediately, the tank should refill and stop. Listen for ten minutes to confirm silence.
8. Remove Mineral Deposits. If the toilet runs intermittently, the flapper is sealing but then leaking after a few minutes. This means the flapper or flush valve seat has mineral buildup. Turn off water, drain tank, and scrub the valve seat with a green scrubbing pad. Wipe clean, then reassemble. A smooth seat makes all the difference.