How to Fix a Running Toilet

By Beth Krietsch

Knowing how to fix a running toilet can help homeowners and renters save time and money. When neglected, a running toilet can waste hundreds of gallons of water per day and increase your water bill. Not to mention, it’s extremely annoying to listen to a running toilet all day. Fortunately, fixing a running toilet is one of those DIY tasks that’s easy to perform. Learn how to fix a running toilet with this troubleshooting guide.

How to fix a running toilet

Whether your toilet is constantly running or cycling on and off, we’ll help you troubleshoot the main issues and determine when professional help is necessary.

The flapper is broken

The flapper is a round, rubber seal connected to the toilet’s flush mechanism and prevents water from leaking into the toilet bowl from the tank. If your tank doesn’t refill or hold water, you probably have a faulty flapper. Open the tank and inspect the flapper—if it’s hard, warped, or broken, you’ll need to replace it as soon as possible.

Another way to determine if you should replace the flapper is to gently push down on it and listen for water to stop running. If the water stops, the flapper may not be sealed properly and will need to be replaced. You can buy a flapper at most hardware stores.

  1. To replace the flapper, shut off the water supply valve under the toilet and flush the toilet to drain most of the water.
  2. Detach the old flapper and insert the new one in its place.
  3. Hook the flapper chain onto the flush lever arm so there’s just enough slack when the flapper is closed.
  4. Flush the toilet to make sure the water doesn’t continue to run.

The fill valve is leaking

The fill valve controls the flow of water from the water supply into your toilet’s tank. A broken valve can cause a consistent flow of water, leading to consistent refill cycles. Flush the toilet and lift up the float arm when the tank is filling to see if the water stops. Slightly adjust the float arm so the tank stops filling when the water is about an inch below the top of the overflow pipe. Examine the fill valve for a leak. If the fill valve is leaking, you’ll need a replacement.

Determine what type of fill valve you have by looking at your manufacturer’s manual and buy a similar one at your local hardware store. Before replacing the fill valve, turn off the water supply, flush the toilet, and soak up any remaining water from the tank with a dry rag.

  1. Disconnect the water supply line located under the tank and flush your toilet.
  2. Unscrew the fill valve lock nut to disconnect the old fill valve.
  3. Insert the new fill valve into the tank and tighten the lock nut.
  4. Locate the small, white fill tube and attach one end of it to the fill valve. If the fill tube is underwater, cut it back so the tube clears the water level.
  5. Flush the toilet to ensure the toilet has stopped running.

The float is too high

Every toilet tank has a float (often attached to a chain) that rises and falls with the water and lets the toilet pump know when to refill the tank and when to stop. There are two types of floats: the ball float and the cup float (ball floats are more common with older toilets).

In general, water will fill to an inch or half inch below the overflow tube. If the water doesn’t stop running or fills above the overflow tube, this is a sign that the float may be too high and needs to be lowered.

  1. To fix a float, either bend the rod that connects the float to the pump or use a screwdriver to adjust the screw on top of the toilet fill valve. When you turn this screw, you can adjust the height of the float.
  2. Using a screwdriver, turn the screw counterclockwise to lower the float and the water level.
  3. Flush the toilet and let the tank refill. The water level should return to inch below the top of the overflow tube.

The chain is too short

Inside most toilets, a chain is used to connect the flapper with the flush lever. In some instances, the chain will be too short and pull on the flapper, keeping it open and allowing water to leak through. This may not sound like a big deal, but this tiny problem can result in hundreds of gallons of water wasted each month.

If you open the tank and see that the chain is too short because it caught on something, adjust it by hand. If the chain is too short entirely, you’ll need to go out and buy a longer chain at a hardware or home improvement store. To stop the water from leaking and running in the meantime, adhere to the following steps:

  1. Open the lid of the tank and unhook the chain that connects the flushing lever to the flapper.
  2. Attach one end of a paper clip to the handle and the other end to the chain (pass it through one of the chain’s links).
  3. Flush the toilet to make sure your chain isn’t too long. If it is and prevents the flapper from staying open while the toilet flushes, move the paper clip to a different point on the chain so that it’s a bit shorter.
  4. If the flapper doesn’t seal properly after flushing, you may want to make the chain a bit longer to prevent the water from running endlessly.

Home warranties and toilet repair

If you’re uncomfortable making any of the above fixes, we recommend calling a plumber. While it’s great to take control and ownership over home repair projects, it’s best to call a professional if you’re having difficulty performing these tasks rather than risk making the problem worse.

If you have a home warranty, call your home warranty provider to file a claim on your running toilet. Not only will this save you repair time, but it will also save you money in repair and replacement costs. Most home warranties will cover plumbing and toilet-related issues due to normal wear and tear. Some common plumbing-related issues that are typically covered include:

  • Leaks in sinks, showers, and toilets
  • Repairs to faucets and shower valves
  • Clearing toilet stoppages

Not all home warranty plans are the same, so be sure to read your terms and conditions and understand the limitations and exclusions of your plan.

If you don’t have a home warranty, you’ll be responsible for contacting a professional and covering the total cost of all toilet repairs. To avoid paying exorbitant repair costs, find a reliable provider by reading online reviews or asking for recommendations from trusted friends and neighbors in your area.

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