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What to do if your boiler leaks

A leaking boiler is not something you should ignore. In fact, it is usually an indication of a much more serious problem.

Here we outline what to do if you spot a leak, whether it’s an emergency and if you can fix it by yourself.

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Why is your boiler leaking?

There are many reasons why your boiler may have sprung a leak and not all of them will be a worst-case scenario. However, it’s important to know what you're dealing with before taking the appropriate action. 

Boiler pressure valve

It may be that the pressure is too high, causing the relief valve to start leaking water. Whilst this may look alarming, your boiler is actually doing this to prevent itself from further damage.

Other reasons for excess pressure can include limescale and other obstructions. If the pressure is too high, here's our guide on how to lower your boiler pressure


Many leaks, particularly among older heating units, are the result of corroded pipes or corrosion within the water tank itself. A clue might be leaking water from the base of the boiler.  

If the corrosion is isolated to one component, this usually can be easily fixed by a Gas Safe Registered engineer. Unfortunately, if the corrosion is more widespread, or if it is affecting vital components such as the heat exchanger, then a new boiler is usually needed. 

Temperature Valve

If the leak is coming from the temperature valve, the temperature probe may need replacing. If your heating system is emitting unusually high temperatures then it's highly likely an issue with your temperature valve.

You'll need to have the valve repaired or replaced for the boiler to be working properly again.  

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Loose Joints

Like all appliances, your boiler will suffer natural wear and tear over its lifetime, with loosening joints and pipe connections being one of the most common areas.

This is due to water repeatedly expanding the pipes when the heating is on and contracting them when the water has cooled. To combat this issue, your joints should be tightened on a regular basis - let's say once a month or so. 

Pump Seals

The pump is a vital part of your home’s heating system as it pumps hot water directly to the radiators, taps, towel rails and showers around your home. If the pump isn’t sealed properly, it can wreak havoc on your whole heating system and a leak can occur. 

If you are experiencing an issue with your pump, then it will need to be replaced immediately. 

Poor Installation

Sometimes a leaky boiler is simply down to poor installation. If you are experiencing a leak around the pipes of your newly installed boiler, then it's highly likely the boiler was incorrectly installed.

It's important to check that the person installing your boiler is Gas Safe Registered before they carry out any work- as it's a legal requirement for anyone who works with gas appliances. Here at Boiler Plan, all of our engineers are Gas Safe Registered, so you're in the best hands and can rest easy knowing your next boiler will be fitted efficiently & professionally. 

Is a leaking boiler an emergency? 

While there are different levels of severity, all leaks should be considered an emergency and are an indication that your boiler needs immediate attention.

A leak could cause irreversible  damage, so you should act fast by having it inspected as soon as possible.

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Should I use my boiler if it's leaking?  

Absolutely not, even if it is in the middle of winter and you've got no heating, you should never use a leaky boiler - it won't keep you warm and will likely cause irreversible damage. 

If you notice a leak or see that the pressure has dropped severely over a short time, turn off your water supply & central heating and get in touch with a Gas Safe engineer to repair or replace your boiler. 

How to fix a leaking boiler?

Again, the simple answer is 'do not try to fix a leak yourself'. With so many possible reasons why your boiler could be leaking, it just isn’t worth it.

Attempting a DIY job could do more harm than good and could result in you voiding your warranty. It is much safer to call a local engineer and ensure it is fixed properly.  

Feel free to book your boiler repair  with us - our engineers can be at your door within 24 hours for emergencies. 

Book a boiler repair

How to look after your boiler 

Just like big purchases such as your car, your boiler also needs regular TLC. Having your boiler serviced regularly can prevent any future leaks, or any other nasty surprises down the line for that matter.   

There’s also more on our website about how often you should service your boiler, as well as a full run-through the checks and maintenance that our engineers carry out.