There’s nothing more frustrating than a constantly running toilet. You know it’s probably just a small issue that needs fixing, but calling a plumber can easily cost you $90 or more—before any repairs even begin. On the flip side, if you ignore it, you’ll be wasting gallons of water every day, and your water bill will start to climb fast. Fortunately, fixing a running toilet is much simpler than you might think. Even with no plumbing experience, this is one task you can handle on your own.
Before jumping into any repairs, it’s helpful to understand the basics of how your toilet operates. Here’s a quick rundown of the key parts inside the tank:
Understanding these parts will help you tackle most common issues that cause a toilet to run.
There are a few different reasons why your toilet might be running continuously. The most common issue is a worn-out flapper, but a high water level, water-logged float, or malfunctioning valve can also cause the problem. Fortunately, all of these parts are easily replaceable and available at most hardware stores. The key is figuring out which part is to blame. Start by carefully removing the lid of the tank and setting it aside in a safe spot.
Before attempting any repairs, you’ll need to stop the flow of water to the toilet. Look for the water supply pipe connected to the tank, typically located near the bottom left side. Follow the pipe to find the shutoff valve, which you can close by turning it clockwise until it stops.
A faulty or dirty flapper is one of the most common reasons for a running toilet. The flapper may not be sealing properly due to dirt buildup, warping, or general wear and tear. To check the flapper, unhook it from the pins at the base of the overflow tube. If it’s dirty, soak it in vinegar for about 30 minutes and then scrub it clean with an old toothbrush. If it’s damaged or looks worn out, you’ll need to replace it. Take the old flapper with you to the hardware store to ensure you get the right replacement. Installing a new one is easy—just follow the package instructions.
Sometimes, the problem lies in the chain connected to the flapper. If the chain is too long, it can get stuck under the flapper, preventing it from sealing. Trim off any excess length to avoid this. On the other hand, if the chain is too short, it might be pulling up on the flapper when it shouldn’t, causing water to leak through. Adjust the chain by moving the hook down a few links until it’s just the right length. Some modern toilets use a plastic arm instead of a chain, in which case you can adjust it by moving the arm down a notch.
If both the flapper and chain seem fine but your toilet is still running, check the water level in the tank. If the water level is too high, it will constantly overflow into the tube, causing the toilet to keep running. Turn the water back on and watch to see if water drains into the overflow tube. If it does, you’ll need to lower the float. Adjust the float by loosening the screw where the float arm connects to the fill valve. Turn the screw a quarter turn counterclockwise and then flush to see if the water level adjusts. Continue making small adjustments until the water level is about 1-1.5 inches below the top of the overflow tube.
If the flapper, chain, float, and water level all seem to be functioning properly, the issue might be a faulty fill valve. Fill valves are inexpensive, so it’s usually easier to replace the valve than attempt a repair. Take the old fill valve to the store with you to ensure you get the right fit for your toilet.
To replace the fill valve, first make sure the tank is empty. Disconnect the water supply pipe from the tank using pliers, then unscrew the locknut securing the old fill valve and remove it. Insert the new fill valve, following the instructions provided, and secure it with the locknut. Tighten the locknut by hand and give it an extra half-turn with pliers to make sure it’s secure. Clip the hose from the fill valve onto the overflow tube, reattach the water supply pipe, and turn the water back on. Finally, replace the tank lid and check the water level one last time.