What To Do If Your Toilet Is Not Flushing Properly | Checkatrade
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What to do if your toilet is not flushing properly

It can be so frustrating when your toilet won’t flush properly. We share some of the reasons why to help you troubleshoot the problem.

It’s something most of us take for granted, so when the toilet is not flushing properly, it can be a real pain, especially if it’s the only toilet in the house.

We’ve put together some of the common reasons why your toilet might not be flushing properly to help you diagnose the problem, and get it fixed.

Common reasons why your toilet is not flushing properly

If your toilet won’t flush properly, it could be due to:

  • Insufficient water in the cistern
  • A problem with the flushing mechanism
  • A drainage problem

Scroll down to learn how to investigate each of these issues.

For a quicker fix, use our search function to find a plumber in your local area.

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How to fix a toilet that won’t flush properly

plumber fixing a toilet that won't flush properly

If your toilet won’t flush properly and you’re happy to do a bit of diagnostic work yourself, take a look at some of the common problems it could be.

Tip: First check the problem is not an external issue, i.e. due to your utility supplier, by checking your taps work as usual and that your neighbours have running water.

Check the water level

The tank (or cistern) needs enough water for the toilet to flush fully. This level is normally indicated inside the tank itself. Lift the lid off the cistern and flush the toilet. Watch to see that the water rises to the mark.

If the water level does not rise back up to the mark (normally a minimum of 3cms beneath the overflow tube of the tank), the water level is too low.

How to fix it

  • To allow more water in the tank, try gently bending the arm on the float (which is connected to the fill valve). The higher the float, the more water is let into the tank. Flush the toilet once the water level has risen to the right level.

If this intervention does not encourage the cistern to refill, there could be an issue with the supply of water to the cistern.

  • Check that the isolation valve on the supply pipe is open. If in an open position, the notch on the screw on the supply pipe will be in line with the pipe. You can adjust this if needed using a flat head screwdriver.
  • If this still doesn’t fix the problem, the next thing to check is the cold water storage cistern in the loft. This supplies the cold water to the toilet and other cold-water outlets in the bathroom. If the cold taps in the bathroom don’t work, check the ball valve in the storage cistern in the loft and gently move the arm up and down. You’ll know if you’ve fixed the problem as the cistern will start to fill up.

If you need to replace a toilet cistern, check out our how to guide.

Check the flushing mechanism

Toilet flushing mechanism

Lift chain/ lift rod

The lift chain (or lift rod) connects the flush lever (the handle on the outside of the cistern) with the flapper that sits at the bottom of the cistern. When you flush the toilet, the flush lever lifts the rubber flapper, which triggers a flush of water into the toilet bowl.

If you notice that the flush lever feels light, i.e. there’s too much slack in the chain, there’s likely to be a problem with the lift chain (or lift rod).

How to fix it

  • Remove the lid off of the cistern and turn off the water supply to the toilet. Locate the lift chain/rod. Check it is connected properly. If it’s connected, but loose, remove the chain and reattach it to a hole closer to the flush lever. If it’s broken, you’ll need to buy a replacement part from your local DIY merchant.


The rubber flapper sits at the bottom of the cistern and controls the flush mechanism. That is, when the toilet is flushed, the flapper opens, allowing water to flow down into the toilet bowl. And when shut, it allows water to fill up in the cistern.

If water does not enter the toilet bowl when the flush lever is pressed, it could indicate that the flapper is not seated correctly.

If you think it’s the syphon, find out how to replace a toilet syphon.

How to fix it

  • Remove the lid from the cistern and turn off the water supply to the toilet. Locate the flapper and check it is positioned corrected. If you notice it’s damaged or worn, buy and fit a replacement. Flush the toilet to check the issue is fixed.

Check for blocked pipes

Plunger unblocking a toilet

It’s not uncommon for toilet pipes to become blocked over time. This could be due to excessive toilet paper, disposing of items such as baby wipes and cotton pads down the toilet, or the general build-up of waste and debris.

If the toilet bowl is slow to empty, or the flush doesn’t clear the bowl effectively, a blockage might be to blame.

How to fix it

  • First, plunge your toilet. Then flush to see if the problem has been fixed. Stubborn blockages may need further plunging, so repeat this process two or three times.
  • If this fails, use a drain cleaning product. Typically, you simply pour the contents into the toilet bowl, wait the recommended time, and either flush or pour hot water into the bowl. Make sure you follow the instructions on the particular product you buy.

If the toilet is still not flushing properly, or if you’re in any doubt, it’s always best to call in the professionals. You could end up causing damage that makes the repair more costly.

The average cost of unblocking a toilet is around £112.50. You can easily find a qualified plumber in your local area using our quick search function, below.


Why is my toilet running but not flushing?

To fix a toilet that won’t flush, remove the lid from the cistern and check 1. the water level, 2. the lift chain, 3. the flapper. If the water level is too low, the toilet won’t flush properly. Gently move the ball valve up and down. Check the lift chain is connected properly and that the flapper is seated correctly. It could be that the toilet is blocked. Reach for a plunger and a drain cleaner. If in doubt, call in a plumber.

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