EXPERT ADVICE
How to deal with a leak from a toilet waste pipe
Updated 07/26
By: Tommy Burgess
Reviewed: Kim Staples
If you’ve noticed a leak from your toilet waste pipe, you’ll want to get it fixed as soon as you can. To help you get it sorted, we’ve put together our top tips and advice on how to deal with a leaky toilet waste pipe.
The main causes of a leaking toilet waste pipe
How to fix it step by step
How to tell whether the leak is coming from the pan connector
How to tell if it's a high-priority repair
What it typically costs to get fixed
When to call a plumber and how to find one
A leak from your toilet's waste pipe isn't something to leave for later. As well as water damage, you're dealing with wastewater, which makes it a higher-priority fix than most household leaks.
Here's how to find the cause and get it sorted.
Main causes of a leak from a toilet waste pipe
A leaking soil pipe in your toilet is usually caused by wear and tear, damage, or incorrect installation.
To help you understand and fix the problem, here are some of the most common causes of a toilet leaking at the waste pipe:
Worn-out seals or washers – It’s normal that, over time, the rubber seals or washers that connect your toilet to the waste pipe can wear or crack causing a leak
The waste pipe is not aligned properly – Poor installation or movement over time can leave your pipe and toilet misaligned, creating gaps that then allow water to escape
Pressure build-up – If your waste pipe gets blocked, it can cause pressure to build up, which can force water out through weak points or seals in the pipe
Damaged pipes – The waste pipe may have been cracked by physical impact, or old pipework might have weakened over time, leading to a leak from the toilet waste pipe
Loose connections – Sometimes, the connections between sections of the waste pipe become loose, creating gaps where water can leak out of
Rusted metal pipes – If you have a metal waste pipe, it may have corroded and developed cracks or holes
Poor quality materials – Low-quality fittings can often suffer from premature cracking and deterioration, which can cause a leak from the toilet waste pipe
You can quickly address the issue and stop the leak by identifying the exact cause of your leaky toilet waste pipe. Or, even better, contact a local plumber to take a look.
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How to fix a leaking toilet waste pipe
For the best and quickest results, it's always best to hire a plumber to fix a leaking pipe.
But if you’re a confident DIY enthusiast, you may be looking to repair your waste pipe yourself. Here are some steps you can try.
1. Identify the cause of the leak
You’ll first need to find exactly where the leak is and what’s causing it. If it’s a minor leak, you might be able to fix it by tightening or sealing the pipe.
If it’s a major leak, you’ll likely need to replace a section of the pipe - or the whole pipe.
2. Turn off your water supply
Before working on your toilet’s leaking soil pipe, locate the shut-off valve and stop the water flow to your toilet.
The shut-off valve is usually located near the base of the toilet.
Once you’ve turned off the water, drain the toilet by flushing the toilet to empty the cistern and toilet bowl.
3. Access the waste pipe
To get proper access to the leaky toilet waste pipe, you may need to remove the toilet.
If so, you’ll need to unscrew it from the floor and carefully lift it off the waste pipe. Then make sure the area around the pipe is clear and accessible.
4. Repair your leaking toilet waste pipe
Some of the actions you might need to take include:
Tightening joints with a pipe wrench or adjustable spanner
Replacing any damaged seals or washers
Sealing the joints of your waste pipe with plumber's putty or silicone
Replacing damaged sections of waste pipe by cutting out any damaged sections using a pipe cutter or hacksaw
5. Reinstall the toilet
Once you’ve done the necessary repairs, replace your toilet (if you removed it) and reattach it to the floor.
Turn the water supply back on by opening the shut-off valve and allow your toilet’s cistern to fill.
If you did remove your toilet to repair the leaky soil pipe, apply silicone sealant around the base to prevent water from leaking onto the floor.
6. Test your toilet
With your toilet back in position with access to water flow, it’s time to test if the leak has been fixed.
Flush the toilet several times and check for any signs of a leak. Hopefully, everything should now be working without a leak in sight.
Leaking toilet - Find the causes, limit the damage and get it fixed
Whether your toilet is leaking at the base or toilet water is leaking into the bowl, if you don't get the problem fixed asap, it can cause significant damage to your home.
Toilet still leaking at the waste pipe?
If you still have a leak from the toilet waste pipe after trying to fix it, it’s time to hire a plumber. And, luckily, you’re in the perfect place to search for plumbers near you.
Only trades who pass our checks and meet our standards are on Checkatrade. Enter your postcode to see plumbers who work in your area. You can browse tradespeople, gather quotes, and get in touch straight away.
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FAQs
The most common causes are worn seals or washers, misaligned pipework, pressure build-up, damaged pipes, loose connections, corroded metal pipes, or poor-quality fittings. Speak to a local plumber to identify the exact cause.
Outdoor leaks are usually caused by a cracked pipe, a blockage, loose connections, or worn-out seals - the same causes as an indoor leak, just further along the run.
Your best option is to hire a plumber to inspect and repair it as soon as possible.
A worn seal at the pan connector is the most common cause. Once the seal has deteriorated, it needs replacing rather than just tightened, to properly restore the watertight connection.
It's generally considered a high-priority issue rather than a true emergency, but should be dealt with as soon as possible.
Beyond water damage, you're dealing with wastewater, which brings a genuine health risk if it isn't dealt with promptly.
Yes - a proper watertight seal at every connection is essential to how the toilet works and to prevent sewage leaks, so this is one repair worth doing properly rather than with a quick temporary fix.
Costs depend on whether it's a simple reseal or a full pipe replacement. See our plumber cost guide for current UK rates by job type.
Most leaking toilet repairs are a job for a plumber, but if the leak has already caused floor damage, you may also need a flooring specialist to make good afterwards.
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