Updated on 25th May, 2023 by Martin Astley
An overflow pipe is an addition to the storage tank or cistern that stops the water from overflowing. It plays an essential role in your home’s water storage systems. You are ensuring that your house does not get flooded with water. Thus, the pipe is sometimes extended from the rear of the place where the water is discharged.
If your overflow pipe is leaking and you cannot identify the reason behind the problem, this article will tell you in detail why your overflow pipe is leaking, where the water collects, and the steps you should take.
To check for an overflow leaking pipe, see where the water collects.
Some plumbing systems that have an overflow pipe are:
- Copper Cylinders
- Toilet Tanks
- Coldwater Feed
- Enlargement Tank
- Sinks and Baths
Why Is The Overflow Pipe Leaking?
The overflow pipe leaking outside is an alarming situation when it comes to your plumbing systems even though it may be a small leak. Prolonged leaks might result in a water overflow and unnecessary mould. This could mean you must switch the entire plumbing system off if it is not taken care of immediately.
Thus, dealing with any issues as soon as they occur is advisable. If you can navigate where the leak is, then many problems can be easily dealt with. Simply follow our step-by-step guide. The following are the most common causes of leaks you need to watch out for:
1. Check The Water Pressure
Increased pressure is the most obvious explanation for leaky pipes. If the water pressure is higher than what the pipe can handle, the tube is going to leak. There’s a valve within the overflow pipe that checks the pressure and the flow of water. Although, the valve might get loose. The reason is a constant increase in pressure, or the pipe might be damaged due to constant leakage.
2. Determine Which Tank Pipe Is Overflowing
If the outflow is at ground level, then it means that your toilet pipe is overflowing. And if you notice water dripping from over the roof. Then it might be your heating system feed or the enlargement tank’s pipe overflowing.
If you’re still not sure on which pipe needs fixing? Then you’ll need to keep checking the tanks and cisterns’ water levels. Or simply call a gas-safe certified engineer to help you figure it out.
3. Analyze The Float Valve and Washer
Washers tend to wear out, as they’re in contact with water. Few cheap, low-quality washers can also be the culprit behind leaks. As they do not last long and result in leaking and other plumbing damage. Replace the washers in such cases, and you’re good to go.
Check that the float valve is not stuck and is flowing. If not so, try to release it. You should also check for damages to the float valve. It might be damaged or might have a leak or a hole. Please don’t ignore it even if the ball is almost broken because it could lead to complicated plumbing problems over time, including leaks reaching tiles, electrics, and the ceiling. Replace the float valve if found broken.
Replacing a float valve is not difficult and can be done as soon as a broken valve is detected.
4. Ways To Switch The Valve Off
Once you are aware of where the problem is around the float valve or washer, you ought to replace it. But before that, you should prevent the water from flowing into the tank, so there’s no excess water loss.
- Shut the water flow through the isolation valve that’s within the pipe that ends up in the tank.
- Flush the toilet to empty the water.
- Stop the water, not the water tanks, by blocking most of the water out at the turncock.
- Drain the remaining water by turning on the facets of your toilet.
- Drain enough water that the level reaches below the area you would like to repair.
5. Toilet Overflow Pipe
The toilet overflow pipe ends outside the house and will overflow if the water flow within the tank/cistern doesn’t stop. There are multiple fixes for this:
Check For The Float Valve; If it’s Freely Moving:
The float valve might be twisted within the valve chain.
Regulate the Float Valve:
The float valve’s height might be set too high to shut most of the water systems off. For that, you’ll have to control the extent of the float valve by bending the arm of it’s metal or adjust it by screws if it’s plastic.
Check for Water Pressure:
The overflow pipe might be leaking due to multiplied water pressure within the pipe, for that check the isolation valve and close it off to manage the flow.
Replace the Float Valve or Washer:
If it is still leaking, then there may be damage within the valve itself or the washer. For that, you’ll have to follow the steps mentioned above to replace the washer or the float valve.
Related: How to unblock a toilet
6- Coldwater Feed And Expansion Tank Overflowing Pipe Leak
The cold-water feed and enlargement tank overflow pipe extend through the massive water cistern to outside your house. The tank provides water to sinks. If any of the system’s overflow pipe is leaky, then these might be the following causes:
The water inlet in the tank is not turning off
Peek inside the tank. And if there is a constant drip from the water feed, try adjusting the float valve or replacing the valve, or washer.
Water is being pressured back to the outlet pipe:
If the pipes are working fine and the float/washer is also fine. Then the only reason for the leak could be that the water is being pushed back from the outlet pipes leading to a leak. This problem will be resolved by calling a gas-safe professional.
7- Overflowing Pipe Of Central Heating Feed
The overflow pipe from the central heating feed also extends to the loft outside your house. The feed supplies water to the central heating system of the house, and if the system’s overflow pipe is leaking, then there are two possible reasons for that:
The water feed is not stopping into the tank
If you see constant water dripping into the tank, ensure the float valve is not damaged, or the washer is not worn off. If you observe such issues, follow the above-mentioned step of replacing the float valve and washer.
Problem with a hot cylinder
If your cold-water feed is working fine, and the float valve and washer are also undamaged, then the only cause for the overflow could be because of some issues with your hot water cylinder.
8- Boiler Overflow Pipe Leaking
Boilers also have a pipe that resembles an overflow pipe consisting of a pressure relief valve. This valve releases water when the system is under too much pressure. The pipe has its end outside your house to prevent any flooding. But the valve only flows when there is a problem in the system. So, if you see this valve leaking, you should immediately take notice.
Note: Do not mistake the pressure valve pipe with a condense pipe as there is a condense pipe that flows when the central heating system is turned on, and hot water flows through those pipes
The pipe might leak because of excessive pressure to the system or because of issues with the pressure valve. In both cases, it is highly advised to call professionals for service.
9- Kitchen Sink Overflow Pipe Leaking
The overflow pipe of the sink is located below the sink that has its opening down the drain. This pipe prevents your sinks from overflowing. So, if there is a problem with the sink overflow pipe you won’t be able to point it out. But the problem indications surface with your sink or baths. If you observe any problem with the drain, the simple step for it is to unclog it and let the sink drain.
Is a leaking overflow pipe dangerous?
A leaking overflow pipe is not that dangerous, but if left unattended, it can cause severe damage to your walls and foundations. However, if you find a leakage problem from an overflow pipe connected to your boiler, this is alarming, as pipes carrying heated water can be dangerous.
Sometimes, the problem may be related to the high pressure or an issue with the valves. So, you should immediately contact a Gas Safe engineer to deal with the problem; as boilers are complex systems dealing with water, electricity, and heat; you will never know how severe the problem is or what’s causing it.
So, after listing all the problems and possible solutions. We hope you will be able to detect your overflowing pipe problems.
Just remember If you observe a problem with your central heating system or cold-water feed or expansion, and you aren’t able to fix it yourself, it will be advisable to call for professional help.
Frequently Asked Questions
Why is my overflow pipe dripping when central heating is on?
Which pipe is dripping excess water outside the house?
Most overflow pipes have an opening outside the house, so if you spot a leaking pipe outside, check for which system’s pipe it is. Follow the guide above.
How do you fix a leaking overflow pipe?
Fixing an overflow pipe consists of multiple steps depending upon how complex the actual issue is. Follow the guide above to find out how to fix an overflow pipe.
What is the purpose of an overflow pipe?
An overflow pipe protects our systems and houses from flooding; hence if our systems go under any damage, the overflow pipe will prevent it by pushing the water out instead of in, inside your house.
What is the size of an overflow pipe?
At Least 9mm in diameter, fitted at a constant fall
How does an overflow drain work?
The overflow opening serves 2 important functions: If the water tap is left on, the opening will channel water down into the drain opening rather than letting it spill out of the sink onto the floor. The overflow allows the sink to drain faster by introducing air into the system.
247 Home Rescue accepts no liability for any injuries or damages you sustain following the advice on this website. If in doubt, seek professional assistance.