Plumbing fixtures

Why Your Toilet Keeps Running, and How to Fix It

Most running toilets come down to a worn flapper, a tangled chain or a bad fill valve. Here's how to tell which.

When your toilet keeps running, it wastes water and is just plain annoying. The good news is that the inside of a toilet tank is pretty simple, and most running toilets come down to one of a few parts. Here's how to find the problem.

How a Toilet Tank Works

When you flush, the handle lifts a chain that raises the flapper, a rubber seal at the bottom of the tank. Water rushes into the bowl. The flapper drops back down and seals. Then the fill valve refills the tank until the float rises and shuts the water off. Any extra water drains down the overflow tube.

A running toilet means water is either leaking out past the flapper or overflowing down the overflow tube.

Find the Cause

Take the tank lid off and set it somewhere safe. Lids are heavy and break easily.

Check the water level

Look at the water in the tank:

• Water is running into the overflow tube: The fill valve or float is set too high or the fill valve is failing.
• Water is below the overflow tube but the toilet still runs: Water is likely leaking past the flapper.

Do the dye test

Put a few drops of food coloring in the tank. Don't flush. Wait about 15 minutes. If color shows up in the bowl, the flapper isn't sealing.

Common Causes and Fixes

1. Chain is too short, too long, or tangled

A chain that's too tight holds the flapper open. A chain that's too long can get caught under the flapper.

Fix: Adjust the chain so there's a little slack, about half an inch, when the flapper is closed.

2. Worn or warped flapper

Flappers wear out over time. They get stiff, warped, or coated with mineral buildup.

Fix:

1. Turn off the water at the shutoff valve behind the toilet.
2. Flush to empty the tank.
3. Unhook the chain and pop the old flapper off its pegs.
4. Take it to the store to match the size and style.
5. Install the new flapper and hook up the chain with a little slack.
6. Turn the water back on and test.

While the tank is empty, wipe the rim of the flush valve where the flapper seals. Buildup there can keep even a new flapper from sealing.

3. Float set too high

If the float lets the water rise too high, water spills down the overflow tube.

Fix: Adjust the float down. On newer fill valves, there's usually a screw or clip on the side. On older ball floats, gently bend the arm down or turn the adjustment screw. The water line should sit about an inch below the top of the overflow tube, or at the line marked inside the tank.

4. Failing fill valve

If adjusting the float doesn't stop the water, or the fill valve hisses or refills slowly, the valve is probably worn out.

Fix: Replacement fill valves are a common part. The job involves shutting off the water, draining the tank, disconnecting the supply line, and swapping the valve. Follow the instructions on the package closely, especially the height setting.

5. Cracked overflow tube

Rare, but it happens. A crack lets water drain constantly. Replacing it usually means taking the tank off the bowl, which is a bigger job.

Safety and Common Mistakes

• Turn off the water first. The shutoff valve is behind the toilet near the floor.
• Don't force a stuck shutoff valve. Old valves can break. Use the main water shutoff instead.
• Don't overtighten. Porcelain cracks. Snug plastic nuts by hand, and tighten tank bolts evenly in small turns.
• Don't use drop-in tank cleaner tablets if the toilet maker advises against them. Some can wear out rubber parts faster.

Signs of a Bigger Problem

Call for help if you notice:

• The toilet rocks or wobbles
• Water around the base of the toilet
• A soft or stained floor near the toilet
• Sewer smell
• The toilet clogs often, or other drains gurgle when it flushes

A wobbly toilet or water at the base often means the wax ring has failed. That can rot the floor underneath. Our guide on soft spots in your floor explains what to look for. Frequent clogs or gurgling drains through the house can mean a sewer line issue, and that's a job for a licensed plumber.

How HLM Can Help

Our toilet repair service covers flappers, fill valves, handles, supply lines, wax rings and resetting or replacing toilets. If there's damage to the floor around it, we can take care of that too with flooring repair. If your faucet is dripping as well, see fix a leaky faucet or call.

Let Us Fix It

Call or text (706) 594-5049, or fill out our free estimate form. Pricing depends on the job, and estimates are free.