A leaking toilet waste pipe can be a frustrating and messy problem to deal with. When a toilet waste pipe starts to leak, it’s important to fix it immediately.
A leaking pipe can lead to water damage inside your house and may even require costly repairs if left unchecked over time. Not only can it cause water damage in your bathroom, but it can also lead to higher water bills.
The good news is that fixing a leaking toilet waste pipe is a relatively simple task that can be completed with a few basic tools and a bit of know-how.
In this article, we will walk you through the steps to fix a leaking toilet waste pipe and get your bathroom back to normal.

How to Replace a Leaking Toilet Waste Pipe
Fixing a leaking toilet waste pipe can be an annoying, messy task. But with these simple instructions, you can get the job done quickly and easily and prevent further damage to your pipes and home.
What You Need
- Gloves
- Spill Tray
- Towel
- New Section of Pipe
Step 1: Locate the Leak
The first step in fixing a leaking toilet waste pipe is to locate the source of the leak. This can typically be done by inspecting the pipe that runs from the base of the toilet and through the outer wall.
Look for any signs of water or moisture around the pipe, as well as any signs of corrosion or damage.
Step 2: Turn Off the Water Supply
Once you have located the leak, the next step is to turn off the water supply to the toilet. This can usually be done by turning the isolation valve located behind the toilet or by shutting off the main water supply to your home.
This will prevent any further water from getting into the pipe while you are working on it.

Step 3: Drain the Toilet Tank
After turning off the water supply, flush the toilet to drain the tank. Once the tank is empty, remove the water supply line from the toilet and place a bucket underneath to catch any remaining water.
Step 4a (Optional): Seal the Joint
In many instances, if it is the joint that is leaking because of a worn or damaged seal, you can choose the simpler (although temporary) option to seal the joint with plumber’s mait (Amazon link – Opens in a new tab).
Starting at the bottom as this is where most of the pressure will be, simply push in a pen or thin screwdriver past the rubber seal and with your finger, insert the plumber’s mait around the seal.
Next, add some of the putty to each side before finally sealing the top. Don’t forget to check again for leaks before completely refilling the bowl again.
Note: By using plumber’s mait, you will be able to leave the toilet pan in place and not have to worry about removing it.
Step 4: Remove the Toilet Pan
Removing the toilet pan is not as scary as it may sound to first-time DIYers. Simply, disconnect the cistern which should have a large plastic nut that can be undone by hand.
Then, remove the nuts from the bolts that hold the toilet pan to the floor. These bolts are located at the base of the toilet and are typically hidden by plastic caps.
Once the nuts are removed, gently lift the toilet pan off of the bolts and set it aside. It is important to be careful when lifting and handling the toilet pan as it can be heavy and fragile.
Note: Don’t forget to place your spill tray underneath to catch any trapped water and prevent mess.
Step 5: Remove the Old Pipe
Waste pipes for toilets in the UK are usually push-fit so you can simply remove the old pipe once the toilet has been removed.
Step 6: Install the New Pipe
Place the new pipe into the hole in the wall where the old one was located.
Step 7: Replace the Toilet Pan
Replace the toilet pan and slowly slide the pipe back into place over the toilet pan outlet. Then screw the pan back into place.

Step 8: Test for Leaks
Test for leaks by pouring a bucket of water or two down the toilet. Probably best to do this rather than refitting everything and having to remove it again.
Step 9: Reinstall the Toilet Tank
Reinstall the toilet tank and reattach the water supply line.
Step 10: Turn the Water Supply Back On
Once the new pipe is installed, turn the water supply back on and check for any leaks. Flush the toilet multiple times. Watch for any signs of water or moisture around the pipe, as well as any signs of poor fitting. If there are no leaks, voila, job done.
Step 11: Clean Up
Remove any debris and clean up the area around the toilet and pipe.
Put all the tools back in the toolbox and make sure the area is clean and safe.
Conclusion
Fixing a leaking toilet waste pipe may seem like a daunting task, but with a few basic tools and a bit of know-how, it can be done quickly and easily.
By following the steps outlined in this article, you can fix a leaking toilet waste pipe and get your bathroom back to normal.
Remember to always take safety precautions and to call a plumber if you are unsure of how to proceed.

Plumbing Wizard Tips
“If you are not confident to tackle this job alone, enlist some help or call in a plumber!”
“If the leak is coming from a crack in the toilet’s outlet at the back, the toilet bowl will need replacing!”
“Whilst you have the toilet pan removed, this is a good time to give the outlet at the back of the toilet a good clean!”
“Check the seals: Make sure that all the seals and gaskets are properly installed and in good condition. These can wear out over time and need to be replaced or temporarily backed up with plumber’s mait!”
Frequently Asked Questions
How do I know if my toilet waste pipe is leaking?
Signs of a leaking toilet waste pipe include water or moisture around the pipe, increased water bills, and water damage in the bathroom.
What causes a toilet waste pipe to leak?
A toilet waste pipe can leak due to corrosion, damage, or worn-out seals and gaskets.
Can I fix a leaking toilet waste pipe myself?
Yes, fixing a leaking toilet waste pipe is a relatively simple task that can be done with a few basic tools and a bit of know-how. However, if you are unsure of how to proceed, it is recommended to call a plumber for assistance.
How long does it take to fix a leaking toilet waste pipe?
The length of time it takes to fix a leaking toilet waste pipe can vary depending on the severity of the leak and the tools and materials needed. On average, it should take around 30-60 minutes.
How much does it cost to fix a leaking toilet waste pipe?
The cost to fix a leaking toilet waste pipe can vary depending on the severity of the leak and the cost of materials. On average, it can range from £10 – £30 if you do it yourself or up to £200 if you call in a plumber.
Do I need to replace the entire pipe if it’s leaking?
Not necessarily, if the leak is small or the pipe is only slightly damaged, it can be temporarily repaired or patched with some plumber’s mait. But if the pipe is corroded or heavily damaged, it should be replaced.
Should I call a plumber if I can’t fix the leaking toilet waste pipe myself?
Yes, it is recommended to call a plumber if you are unsure of how to proceed or if the problem persists. If you are not familiar with the process or not too confident, it’s better to call a professional to avoid causing further damage.
About Me
I’m Lee the Plumbing Wizard. I’ve been a plumber for over 40 years and have seen it all. People used to call me a magician because I could fix things so easily – hence the name Plumbing Wizard. I’m always happy to help, so if you need any advice or just someone to talk about plumbing with, don’t hesitate to get in touch!
