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Roto Rooter Blog

How to Fix a Running Toilet?

Published on:
October 22, 2020

Few things are as frustrating as toilet that keeps running. It's a small problem, but somehow still drives us crazy. The good news is, it’s not usually hard to figure out how to fix a running toilet. Even if you're not normally the do-it-yourself type, you can probably handle this one. 

How much does it cost to fix a running toilet? Not much. Mostly it takes time and a willingness to try out a few things until you know what works.

Toilet Terminology

Take the lid off the back of the tank. The easiest thing to identify is the “float.” It does exactly what the name suggests – when the water rises, it floats up until the "float arm” to which it’s attached shuts off the “fill valve” at the other end.

Flushing the toilet opens up a round, rubber “flapper” that lets the old water rush out at the bottom. Finally, there’s the “overflow tube,” which is connected to the fill valve. It prevents the tank from overflowing, although you’ll notice it’s also where the water fills it up in the first place.

Common Causes of a Running Toilet

What causes a toilet to keep running? One of the most common problems is that the flapper isn’t sealing completely. Water keeps draining out, so the float never rises high enough to shut off the fill valve. 

Try holding the flapper closed (use a stick or ruler if you’re squeamish) to see if that solves the problem. If it does, you need a new flapper. Any local hardware store has these and they’re not expensive or difficult to install. They’re relatively universal, but take a picture with your cell phone for easy reference at the store. You'll feel better. 

When ready, turn off the water to the toilet (there’s a valve right below the tank), flush out what you can, and follow the directions on the packaging. A small pair of pliers may be helpful, but no special tools are required.

If the flapper is fine, the next suspect is the fill valve. Lift up gently on the float before the tank is full and see of the water stops. If so, you need to adjust the float arm. Look for a screw where it attaches to the fill valve or carefully bend it to adjust the angle.

If that doesn’t work, the valve itself may need replacing. This looks intimidating, but the basic process is the same as with a flapper – turn off the water, flush out excess water, and carefully remove the valve assembly. Follow the instructions on the replacement using common household tools.

How much does it cost to fix a running toilet?

Flappers are usually under $10. Fill valves run $20 - $30. Assuming you have basic tools at home, you’re unlikely to need anything else. Most of figuring out how to fix a running toilet is about patience and paying attention and noticing how the parts work together.

Now, take a breath and get started!

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