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How to Fix Running Toilet: Possible Causes and Solutions

A running toilet is among the less noticeable yet expensive toilet problems most users experience. The toilet leaks slowly and silently, and before the owner notices, they have already lost much in the water bill. It’s estimated that a running toilet wastes up to 200 gallons a day.

But how do you fix a running toilet?

Fixing a running toilet depends on the cause of the leak. If the flapper is the cause, you can fix it by installing a new one. If the refill tube is causing water to run continuously, cut it to the correct length. Most of the problems are easy to fix and don’t require a professional.

The article discusses the possible causes of a running toilet and how to fix it. Read on to learn more.

fix running toilet problems

How to Fix Running Toilet? A Step by Step

As soon as you discover the running toilet problem, provide a fix immediately. But since many parts may be causing the leak, you must determine the fault first.

The following are the possible causes of a running toilet and their fixes.

1. Worn Flapper

Toilet flappers, sometimes called seals, are plastic or rubber seals installed at the bottom of the toilet tank. The flapper allows water into the toilet bowl during a flush.

Usually, a flapper can last up to 5 years, but leaking may start by the third year as toilet quality differs. Leaks are due to the worn edges, which bend inward, allowing water to sip through.  


A worn flapper should be replaced, which you can do by following the steps below;

  • Step 1. Drain water from the toilet tank
  • Step 2. Unhook the chain connecting to the flapper from the handle arm
  • Step 3. Unhook the flapper from the joints where it connects to the flush valve and remove it
  • Step 4. Install the new flapper by first hooking it to the flush valve
  • Step 5. Connect the chain from the flapper to the lever
  • Step 6. Test the new flapper by flushing

Depending on the quality, a flapper costs between $5 and $40 and can take up to 30 minutes to install. Hiring a professional can cost more than $50.

The following video shows how to replace a worn toilet flapper.

 2. Short Valve Chain

The valve chain may be the cause of the problem that started after a recent repair or a replacement in the tank. The chain connects to the handle arm and lifts the flapper allowing the water to run.

If the chain reconnected is shorter on the handle arm, the flapper may remain slightly elevated, allowing water to run.


To fix the short-chain connection, you have to adjust its height. Unhook the chain and connect it at an ideal length on the handle arm. Also, in most toilets, the chain is connected to the first hole of the handle arm to avoid leaking. Try to fix it at the closest hole on the arm to fix the leak.

3. Incorrect Height of Refill Tube

Refill tubes allow water into the overflow tube from the fill valve to replenish water in the toilet bowl. These rubber tubes usually come unclipped or cut; the owner or plumber has to prepare them.

If the refill tube is too long, it causes a siphon effect in the overflow tube, causing a continuous leak.


The solution to the incorrect height of the refill tube is to cut it into the correct length. Follow the steps below.

  • Step 1. Turn off the water to the toilet tank
  • Step 2. Disconnect the tube from the fill valve
  • Step 3. Cut the refill tube shorter and fit it with a clip
  • Step 4. Reconnect the refill tube at the fill valve and clip the other end on the overflow tube
  • Step 5. Flush and test for leaks

 4. Fill Valve Not Closing

The fill valve provides water to the toilet tank once the toilet is flushed. The contains a float connected to the adjustment screw holding to the lever arm. The lever arm opens and closes the fill valve when needed.

With time the seal in the fill valve deteriorates and cannot create a complete seal between the outer and the inner pipe, allowing a leak. Mineral deposits caused by water hardness can form inside the refill valve and cause leaks by preventing a tight seal.


The solutions to fill the valve not closing include replacing the seal inside the fill valve and flushing the mineral deposits. Follow the steps below;

  • Step 1. Close the water supply to the water tank and flush
  • Step 2. Disconnect the adjustment screw from the lever arm
  • Step 3. Press the fill valve top inwards and a quarter turn left
  • Step 4. Lift it off
  • Step 5. Inside the valve, remove the seal around the metal stem
  • Step 6. Install a new one
  • Step 7. Turn the water for a few seconds to flush any mineral deposits on the fill valve
  • Step 8. Reconnect the valve back to the pipe
  • Step 9. Reconnect the adjustment screw to the lever arm
  • Step 10. Test

The following video shows the fixes to the fill valve not shutting off.


Following are the questions frequently asked by users on this topic.

Q1. Can Debris and Dirt in The Toilet Tank Cause a Running Toilet?

Yes. Debris and dirt in the toilet water can get into the flush valve seat, causing the flapper not to close correctly. With the flapper slightly open, the water can leak into the toilet bowl.

Q2. How Much Does It Cost to Fix a Running Toilet?

To repair the running water, issue the cost ranges between $50 and $450. The price varies with the failing part and the amount of time it’ll take to buy and repair it.

Q3. Can Failed Piston Cause a Running Toilet Problem?

Yes. In anti-siphon flush toilets, the piston can cause the running toilet problem. The problem happens just after the flush, mostly due to the piston getting stuck in an open position.


A running toilet can cost much in terms of repair money and requires an immediate fix. If you notice your toilet leaking, check the possible causes mentioned above and follow the solutions accordingly.

Repairing this problem doesn’t require a professional, but repair must be sooner if the water is running out fast. During the repair, check the user manual if you bought the toilet new to ensure you buy compatible parts.