How to Stop a Running Toilet

Flushing toilet bowl landscape
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A constantly running toilet is a common problem in many homes, not to mention a major annoyance and detractor from your home’s energy efficiency. Fortunately, addressing this issue is simple and will help you reduce your water usage. Learn how to troubleshoot and fix the cause of your leaks

Understand How Your Toilet Works

A basic understanding of the mechanisms in your toilet and how they work will help you make the necessary repairs.

Here’s a basic rundown of how your toilet flushes:

  • When you press the handle, a chain lifts a flap that allows the water in your tank to flow into the bowl. As the water drains, the flapper drops and closes the opening.
  • A large plastic float drops as the water flows into the bowl. Your float is connected to a float valve that opens when the float is down and closes when the tank is full and the float is up.
  • There is also an overflow tube that drains excess water into the bowl if the levels in the tank get too high.

Locating the Source of Your Leak

Your toilet’s leak can stem from a variety of issues, including faulty flappers, broken fill valves, low or high water levels, water-logged floats and mineral buildup.

Faulty Flappers

Your toilet’s flapper is a plastic or rubber cap that keeps water in your tank. Over time, your flapper can become brittle and create a faulty seal. If your tank doesn’t refill or hold water, it’s likely due to a sub-par flapper.

Here’s how to troubleshoot your flapper:

  • Check the Flapper’s Consistency: In many cases, flappers become hard and stop creating an adequate seal. Feel your flapper to ensure it’s still soft and able to hold back water.
  • Check the Chain: Make sure the chain connected to your flapper isn’t catching on anything. If you have an oversized chain, thread it through a soda straw to eliminate tangles. You can also replace your chain with a loop of dental floss that is the same length as the chain.
  • Check for Jams: Flappers can become pinched in their hinges. Look for a side of the flapper that’s jammed and preventing a full seal.
  • Check for Alignment: Your flapper can become dislodged and cause leaks. Make sure your flapper is seated directly over the drain.

Broken Fill Valves

Your fill valve controls the flow of water into your toilet’s tank. A broken valve will cause a consistent flow of water, which will lead to constant refill cycles. Submerged float valves are the most common sign of a faulty fill valve. Fortunately, replacing your float valve is simple. Here’s a quick how-to:

  • Turn Off Your Water Supply: Turn off your toilet’s water supply and remove your toilet’s lid. Next, flush the toilet and place a plastic bin or bucket below the water supply hose.
  • Remove your fill valve: Unscrew the locking nut on the bottom of the water supply shank and remove the entire valve assembly. Be sure to keep your bin below your work area to catch any additional water drainage.
  • Install Your New Valve: Adjust the height of your new valve to meet the size of your tank. It’s a good idea to keep your fill valve one inch below the tank’s edge. Insert the threaded end of the valve into the base of the tank and tighten the locking nut by hand. Use pliers to turn your nut until you create a watertight seal.
  • Reattach Your Supply Lines: Re-attach your water supply line to the fill valve shank and place the refill tube into the overflow tube. Avoid placing the tube below your water line. This will lead to constant refilling. Most kits come with a clip or angle adapter that will ensure your tube is at the right angle.
  • Turn On Your Water: Turn on your water supply and let the tank refill. Change the height of your float valve to meet your needs and replace the toilet tank’s lid. 

Water Levels

Your toilet’s overflow valve ensures that your tank doesn’t overfill and flood your bathroom. But if your float is set too high, small amounts of water will leak into your overflow tube and into your toilet bowl. This will keep the water in your tank too low, and result in constant refill cycling.

You can fix this problem by adjusting your float.

Ideally, the water level in your tank should be between one-half and one inch below the opening of your overflow tube. Toilets usually have two different kinds of floats. Ball floats are in many older toilet models and use a screw located at the base of the float arm to raise or lower the float.

The lower the ball float, the lower the in-tank water levels. Ball valves can also sometimes crack and become waterlogged. Unscrew your valve and check it for water. Float cups come in newer toilets and are located around the fill valve itself. Many float cups have screws located toward the top of the fill valve that will adjust the height of the cup.

Water-Logged Floats

Water-logged floats can also cause constant running. If water is trapped inside your float, it will sit lower in the water and leave your float valve partially open. Check your float by unscrewing and shaking it. Replace the float if you hear water inside.

Mineral Buildups

Minerals can build up on the mechanisms inside your toilet, causing jams and partial seals. Check the inside of your toilet for obvious deposits of a scummy residue or hard build up. If you spot signs of minerals, it’s best to call a pro. Cleaning your toilet’s flushing system can be difficult and may require taking apart some of the internal components.

When to Call a Pro

It’s important to never hesitate to enlist the help of a pro during any part of your toilet maintenance. A professional plumber will identify the problem and provide the appropriate solutions – without the potential mistakes of a DIY job. In certain circumstances like severe flooding, it’s important to call a pro immediately.