DIY Fix Running Toilet

  • So your toilet is dripping.
  • The sound is keeping you up at night.
  • Your water usage is steadily increasing and you’re wasting money.
  • You’re pulling your hair out and want to fix it yourself.

Although calling a plumber saves you time and potential bigger problems, you’re sure you can fix the running toilet yourself.
Here are the steps to stopping your toilet from running constantly:

► Before you start:

  • Working time: 20 minutes to 1½ hours
  • Total time: 30 minutes to 2 hours
  • Skill Level: Intermediate

As far as fixing your own running toilet goes, this type of job is relatively easy.

Most DIY plumbers may have trouble taking the toilet apart and putting it back together, which is why we suggest someone with plumbing experience.

How does a toilet work?
There are three main parts inside the cistern (tank) which could be the cause of the running toilet:
  1. The overflow tube. This part is designed to prevent the toilet tank from overflowing.
  2. The flush valve. This part is designed for releasing the water inside the tank when the toilet is flushed.
  3. The fill valve. This part is designed to fill the tank.
You may need to replace any of these parts during the toilet repair, so first make sure to find compatible parts. Replacing the overflow tube, flush valve and/or fill valve is minimal and can help you save money on your water bill once you’ve fixed the running or dripping toilet.

Understanding how a toilet works

To explain where the problem may exist with your running toilet, we will explain the working parts and how a toilet works below.
  1. Water fills the the toilet tank through the fill valve tube. This part has a flapper which stops the water from escaping the tank. It is a large gasket at the base of the flush valve that sits in the bottom of the tank.
  2. As the tank fills, the float rod or float mechanism rises with the water, and when it reaches the set water level, the fill valve stops the intake of water. If the water continues to rise beyond this point, it will begin to spill into the overflow tube, which is designed to prevent flooding by draining water before the tank can overflow.
  3. Now that the tank is full and the water has stopped filling up, the toilet can be flushed. Pressing down on the handle or button pulls a chain that is attached to the flush valve flapper which then opens and releases the water that is inside the tank.
  4. The water then rushes into the toilet bowl through evenly spaced rim holes and may have a secondary entry point known as a siphon jet to help increase the strength of the water being flushed.
  5. As water enters the toilet bowl the water level increases, allowing it to flow through the S-trap and down the main drain.
  6. The water continues to flow until the tank empties. The flush valve flapper then drops down again and seals the toilet tank.
Running Toilet Causes

How do you fix a toilet that keeps running?

If your toilet won’t stop running, run through these 7 quick steps:
  1. Turn off the water supply at the shutoff valve below the toilet.
  2. Remove the tank lid of the tank and put it somewhere out of the way where it won’t get damaged.
  3. Read below: Identifying the running toilet causes
  4. Read below: Fault finding checklist
  5. Repair the leak once you have identified where the water is leaking using the methods above.
  6. Turn the water supply back on.
  7. Replace the tank lid back on the toilet.
    Plumber detecting plumbing problems with blue dye tablets.  https://bluedyetablets.com/the-surprising-way-blue-dye-tablets-can-detect-plumbing-problems/

    Identifying the running toilet causes

    If a toilet is constantly running this means that the system is either allowing water to pass through the flush valve flapper or that the water within the tank is flowing into the overflow tube. You can quickly check whether the excess water is flowing into the toilet bowl or into the overflow tube by putting a few drops of dye into the tank or by using blue dye tablets.
    • If the colored water flows into the toilet bowl, then the flush valve or flapper mechanism is faulty.
    • If the water in the toilet bowl remains clear, then the fill valve or overflow tube system is your cause.
    Parts of a toilet tank. Fault finding checklist - how to fix a running toilet

    Fault finding checklist

    When fault finding the cause of your running toilet be sure to go through this list and inspect each of these 7 items.
    1 - Toilet constantly running - flapper broken

    1) The toilet flapper isn’t closing.

    A loose or broken flapper can cause your toilet to keep running. The main source of a toilet that keeps running is that the toilet flapper isn’t properly closing. The flapper is worn out and therefore does not properly seal. Begin by pushing down slightly in the middle of the flapper while it’s in the tank and see if the water stops running. Inspect the flapper and make sure it is free of any build-up or residue; removing the build-up could solve your problem. Toilet flappers come in different sizes, so make sure to turn off the water shutoff valve at the main water line first before removing it. If you don’t find any other obvious causes, replace the toilet flapper. Use this as a sample and get the fitting replaced. It’s also a good idea to know what type of toilet you have. Next, check the flush valve (what the flapper sits on) for any cracks or damage. If you see any damage to the flush valve, it will need to be replaced. If there looks like there is build-up, give the flush valve a wipe to see if the build-up can be easily removed.
    2 - Running toilet - refill tube

    2) The refill tube is too long.

    Your refill tube (or fill tube) should sit on top of the overflow pipe, or else it could cause your toilet to run constantly.

    This is the tube that runs from the toilet fill valve into the overflow tube. If the refill tube is too long, the water will go from the toilet tank to the overflow valve, causing your tank to run continuously. This may also cause what is known as ghost flushing. No, you don’t have ghosts in your toilet… but it sounds like your toilet is flushing on its own every so often.

    The reason for this is because the refill tube is too long and it creates a siphoning effect from the tank into the overflow tube. The tube should be sitting just above the overflow tube. You can install clips. If you purchased a toilet fill valve, you might have one already. The refill tube to be sitting just above the overflow tube. Otherwise, it will pull water from the tank into the tube.

    3 - Adjust float to fix running toilet

    3) The float is set too high.

    Use a screwdriver to adjust the height of your float cup so the toilet stops running.

    Another reason that your toilet keeps running is that the float is too high. This can happen if the toilet float arm is bent or the float ball is stuck above the water level. This can happen on older-model toilets that have a ball float rather than a float valve.

    To fix this, adjust the float arm in the float ball to the right level so that it shuts off after the water is at the correct level on the tank. There will be a screw on the top of the fill valve that can adjust the float ball’s height.

    If you have a newer model, the float cup on the float valve may be set too high, and you will need to adjust it to a lower water level. If the float cup is set too high, then the water will keep running into the overflow pipe, causing water to run continuously.
    This can also happen if your toilet was previously filling up slowly and you replaced the fill valve. By replacing the fill valve, you may have set the float cup too high, and that is why it’s now running constantly.

    4 - Fixing a running toilet - toilet chain too short

    4) The flapper chain is too short.


    Make sure your toilet chain is not too long or too short when fixing your running toilet.

    Another reason for the flapper not closing is that on certain toilets that use a chain, the distance from the lift arm and flapper may be too short. If there is not enough slack in the chain then the flapper will not close completely and properly close the seal. This causes water to go down the drain valve and into the toilet bowl.

    5 - Toilet chain is too long - toilet keeps running

    5) The flapper chain is too long.

    The opposite can also happen if the flapper chain is too long. The slack in the chain could get caught in between the flapper and the drain valve, causing the flapper not to seal properly, and the water will continue to run.

    If your toilet occasionally keeps running, it could be that the chain is sometimes getting stuck in between the flapper in the drain valve, and other times does not. To fix this, shorten the chain.

    6 - Broken float valve in toilet

    6) Broken float valve


    Inspect the fill valve and fill tube closely. If the casing is cracked it will result in water leaking continuously. If this is the case, you will need to replace the fill valve with a newer model. Replacement fill and float valves are not expensive or difficult to replace.

    7 - Toilet overflow tube - overflow pipe cracked

    7) The overflow pipe is cracked.


    If the overflow pipe or overflow tube is cracked the water will leak through the overflow and down into the bowl. This causes the toilet to run or even occasionally run.

    A running toilet shouldn’t be ignored for too long. Most often fixing a toilet is an easy fix that you can do yourself and with minimal tools and a few step-by-step instructions.

    If you have tried these steps and cannot fix the running toilet, you may need to bring in a professional plumber to help you with further identifying the problem.

    We are here to help, so call us and we’ll be there as soon as plumbingly possible.