Does the bowl of your dual flush toilet somewhat resemble Niagara Falls? Then put an end to the constant draining with the 3 methods in this article.

If your dual flush toilet is continually running, do the following.

  1. Replace or fix the toilet seal
  2. Adjust the tank’s water level
  3. Replace the fill valve

Are you ready to see the step-by-step instructions for each of these methods? Then make sure you check out what’s coming up next.

Three Methods to Fix Your Dual Flush Toilet

If you’ve landed here it means that your toilet is flushing relentlessly and you are keen to do something about it. It’s not just the noise of a constantly running toilet that’s annoying. What’s even more frustrating is the inevitable sky-high cost of having the toilet flushing gallons of water all day long.

That’s why coming up, you’ll find 3 methods that will help you to fix your dual flush toilet. Let’s get right to it.

#1 Replace or Fix the Toilet Seal

The most common culprit of a continuously running toilet is its seal. There may be a couple of reasons why your toilet’s seal isn’t working properly. The following is a list of possible seal problems and what you can do to fix them.

The Problem With the Seal What You Should Do
It is misaligned
Fix it by realigning the seal  
It is dirty or clogged with limescale Remove the seal to clean it then put it back in place
It has hardened over time   It is broken Replace the seal with a new one  
It is broken

Ok, but the question now arises. How can you go about fixing or replacing your dual flush toilet seal? The following method will walk you through realigning, cleaning, and replacing your toilet seal. The only equipment you’ll need for the job is a new seal (if yours is faulty). You should be able to find an inexpensive one at any good hardware store.

Whatever the problem with your seal, fix it with the following steps.

  1. Turn off the water supply to the toilet. You can usually find the stop valve behind the toilet.
  2. Press and hold the dual flush down to remove as much water from the toilet as possible
  3. Remove the lid from the toilet tank
  4. Hold the valve firmly while turning it anticlockwise to remove it
  5. Check and see if the seal is misaligned. If it is, move it into the right place.
  6. If the seal was not misaligned, remove it by pulling on it
  7. Examine to see whether it is dirty or covered in limescale. If the seal is dirty or scaled up, run it under water to wash it then put it back in place. This may be a job that you have to do periodically if you live in a particularly hard water area.
  8. If the seal is hard and brittle or broken, you will need to replace it. Slide a new seal onto the valve.
  9. Put the valve back into place
  10. Put the lid back on the tank
  11. Turn the water supply to the toilet on again. Wait for the water to refill in the tank.
  12. Flush the toilet a couple of times to check that you are happy with the result
removed lid from the toilet tank
Step 3: Remove the lid from the toilet tank

#2 Adjust the Tank’s Water Level

Another reason why your toilet is running could be because of an excess level of water in the tank. If the water in the tank keeps overfilling, your toilet will continue flushing to get rid of the excess.

Here is everything you need to do to adjust the water level in your toilet’s tank. You won’t need any tools for this fix.

  1. Turn off the water supply to the toilet. You can usually find the stop valve behind the toilet.
  2. Press and hold the dual flush down to remove as much water from the toilet as possible
  3. Remove the lid from the toilet tank
  4. Locate the plastic screw beside the toilet float
  5. Turn the screw anticlockwise
  6. Open the water supply to the toilet and wait for the water to fill back up. See how far the water fills up in the tank. (With the screw loosened, it should not fill as high as it did before.)
  7. Turn the screw slowly clockwise to tighten it. Tighten the screw until the water level reaches the optimum height.
  8. Put the lid back on the tank
  9. Flush the toilet a couple of times to check that you are happy with the result
flushing of toilet
Flush the toilet a couple of times to check that it is draining well

#3 Replace the Fill Valve

One last, common reason why homeowners have problems with their toilets constantly flushing is that the fill valve is faulty.

It is possible for you to fix your fill valve, but it is a fiddly job. It is also sometimes hard to find the individual parts you need for the job without buying a whole new fill valve kit.

However, new fill valves are easy to get hold of and are inexpensive. This could mean that buying parts to fix an old one might turn out to be more hassle than it’s worth. That’s why I recommend you replace your faulty fill valve instead of repairing it. 

To replace a broken fill valve you will need the following tools.

You Will Need

  • Toilet fill valve kit
  • Adjustable wrench
  • Towel
  • A small bucket
  • Screwdriver

To fix the refill valve, follow these steps.

  1. Turn off the water supply to the toilet. You can usually find the stop valve behind the toilet.
  2. Press and hold the dual flush down to remove as much water from the toilet as possible
  3. Remove the lid from the toilet tank
  4. Remove the float from the toilet
  5. Use a towel to mop up the excess water in the toilet tank. Try to get rid of as much water as you can.
  6. Place the bucket underneath the fill valve. You will use this to catch any water that runs from the toilet tank.
  7. Remove the fill valve by using an adjustable wrench to remove the mounting nut on the side of the toilet.
  8. Take out the old valve inside the tank by pulling on it
  9. Prepare the new fill valve. Adjust the height on it so that the marking on the new fill valve is at least 1 inch above the overflow tube.
  10. Insert the bottom of the valve into the toilet opening and push down. It should sit flush on the floor of the tank.
  11. Tighten the locking nut on the outside of the toilet. Use a wrench to tighten it.
  12. Attach the refill tube to the overflow pipe. You can use your wrench here too.
  13. Reattach the fill valve
  14. Turn the water supply back on. Wait for the tank to fill.
  15. Flush the toilet a couple of times to check that the new fill valve is working properly
Toilet refill tube
Insert the refill tube into the overflow pipe

Are you a visual learner like me? Then perhaps you would rather watch these steps as they are completed. If so, take a look at this quick tutorial video.

Conclusion

A dual flush toilet that doesn’t stop draining is something that will make us feel concerned. But as you’ve seen thanks to the 3 methods in this article, it doesn’t have to be a complex problem to fix. I’m sure the step-by-step instructions have helped you to get your WC back in proper working order.

If this article has helped you, then why not check out some of our other articles and free guides. You can even sign up to our email list.

Have a great day!

-Craig