A running toilet is one of the most common and most annoying household problems. That constant sound of water trickling is not just irritating — it’s expensive. A running toilet can waste up to 200 gallons of water per day, which adds serious money to your water bill every single month.
The good news is that almost every running toilet can be fixed in under an hour with basic tools and parts that cost less than $20. You don’t need a plumber. You just need to know what you’re looking for.
Why Is My Toilet Running?
There are three main causes. The first and most common is a worn flapper. The flapper is the rubber seal at the bottom of the tank that opens when you flush and closes to let the tank refill. Over time the rubber degrades and it no longer creates a watertight seal. Water slowly leaks through into the bowl and the fill valve keeps running to compensate.
The second cause is a faulty fill valve. When it wears out it either runs constantly or makes a hissing sound.
The third cause is a float that’s set too high. If it’s set too high the water level rises above the overflow tube and drains continuously into the bowl.
What You’ll Need
A replacement toilet flapper, an adjustable wrench, rubber gloves, and a towel.
Step 1: Diagnose the Problem
Remove the tank lid. Put a few drops of food coloring in the tank. If color appears in the bowl without flushing, the flapper is leaking.
Step 2: Turn Off the Water Supply
Find the shut-off valve behind the toilet near the floor. Turn clockwise until water stops. Flush once to empty the tank.
Step 3: Replace the Flapper
Unhook the flapper from the two pegs on either side of the overflow tube. Disconnect the chain from the flush handle arm. Snap the new flapper onto the pegs and reconnect the chain with half an inch of slack.
Step 4: Adjust the Float
The water level should sit one inch below the top of the overflow tube. Adjust the float arm or clip downward if needed.
Step 5: Replace the Fill Valve if Needed
If the toilet still runs after replacing the flapper, replace the fill valve kit. Turn off water, disconnect the supply line, unscrew the locknut, lift out the old valve, insert the new one, reconnect, and adjust the water level.
Step 6: Test
Turn water back on, let the tank fill, flush once, and listen. The fill valve should stop completely when the tank is full.