Category - Boilers
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Will Scholfield, Engineer

31 Jan : Updated 19 Apr ● 7 min read

Is a leaking boiler an emergency?

A leaking boiler is an emergency that requires urgent attention from a professional engineer.

If you notice your boiler is leaking water, you might be tempted to ignore it and place a bucket under the leak, at least in the short term. However, it’s important to know that a boiler leak will require the expertise of a Gas Safe registered engineer ASAP and that it could pose a serious risk, depending on the cause.

Be sure to understand the difference between a leaking boiler and a leaking radiator or pipe that’s feeding a radiator. While the latter is something that needs to be looked at, it isn’t regarded as an emergency.

You also need to remember that a boiler can leak both water and gas, despite most leaks being water.

If you can smell gas or think there could be a gas leak from your boiler, you should call the National Gas Emergency Service immediately on 0800 111 999. This service is available 24/7.

If your boiler pressure keeps dropping or central heating system is not working properly, you could be dealing with a boiler leak, but you need to know what does and doesn’t mean you need to call out an engineer straight away and what’s safe to get sorted as soon as possible, but can be left in the immediate term.

In this article, we will look at why a boiler leaking water is considered an emergency and what you can do to ensure you’re not without heating and hot water for too long.

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Why are boiler leaks so dangerous?

With constant use or due to an installation fault, your boiler could be facing a serious fault when a leak is found. A dripping boiler is one thing, however, a boiler that has become dangerous due to its faults needs to be handled with care and expertise.

A boiler leaking water needs to be looked at urgently by a Gas Safe engineer.

Fortunately, a leaking boiler is usually relatively obvious and can be picked up early. This means that an internal leak may not have time to cause damage to other components including electrical and corrosion issues. 

Below are some of the main reasons why a boiler leak is considered dangerous.

Boiler leaks can be a health hazard

Your boiler leaking for an extended period could result in the growth of fungi or mould. These growths release spores into the air, which is hazardous to humans.

Fungi and mould grow fast in damp conditions and can cause mild to severe health issues like coughing, asthma, and difficulty breathing.

Damage to the structure of your home

Water leaks left untreated will cause damage to your home.

Water puddles can cause stains on walls and floors and warp wooden beams. Water repeatedly expanding and shrinking in cold climates will also cause structural damage to wooden supports in the house.

If you do not fix your boiler’s leak, parts of your house can become completely rotten.

Should I use my boiler if it's leaking? 

If you have discovered a boiler leak, it is best to switch off the water supply and central heating. Place buckets under the leaks and dry any water spills. 

If it is a gas leak that you suspect, turn off your gas supply; this is usually done at the isolation valve, a lever on your gas meter. 

If you can smell gas or think there could be a gas leak from your boiler, you should call the National Gas Emergency Service immediately on 0800 111 999. This service is available 24/7.

Once you have taken these steps, you should immediately contact a gas safe engineer to come to check out your boiler.

Common causes of boiler leaking water

Most boilers will start to leak water because of their age, but there could be other reasons:

Corroded or poorly installed pipework

The pipes underneath the boiler are usually the main culprit for a leaking boiler, with leaks often being due to corroded pipes. With time, the water and debris in the system will corrode the copper piping. This creates small gaps for the water to leak from. 

However, if your boiler is new, this probably isn’t the case. Instead, it’s likely that the pipes weren’t quite fitted correctly. 

Corrosion to the system

If just one pipe is corroded, then it should be relatively simple for a Gas Safe engineer to replace it. 

Pressure relief valve

When you see water leaking from the pressure relief valve (usually a small copper pipe outside the property on the other side of the boiler in most cases), it is probably because the pressure in the boiler is too high. The pressure relief valve is responsible for maintaining the water pressure and prevents the pressure from getting too high.

You will have to call out a Gas Safe registered engineer with a Gas Safety certificate to come to investigate the cause of water leaking from the pressure relief valve.

Loose joints and damaged seals

This is part of the natural wear and tear associated with boilers. Over time, joints and seals loosen or decay due to water repeatedly expanding and contracting. They will need to be looked over by an engineer to prevent water leakages. 

What should I do if my boiler is leaking water?

If you notice water dripping from any part of your boiler, your first step should be to contact a qualified professional to check the severity of the problem. Until the professional arrives, there are some things you can do:

  1. Turn off the water supply and heating system.

  2. Clean up any water once all electrical components have been switched off.

  3. Wait for the heating engineer to arrive.

How can I prevent my boiler from leaking again?

The best way to prevent future leaks is to maintain your boiler, check it often, and get an annual boiler service. These services are usually included as part of a boiler cover plan.

Here are some measures you can take to prevent future leaks:

  1. Annual services. Servicing your boiler each year means any faults or potential for leaks can be spotted before it becomes a big problem.

  2. Chemical flush. You can flush your boiler to prevent the build-up of any limescale and debris in the pipes and boiler.

  3. Magnetic filter. A magnetic filter works with magnets that attract magnetic debris in the boiler and heating system.

How to fix a leaking boiler

You should always call out a Gas Safe engineer to a leaking boiler and you should not attempt to fix this problem yourself.

However, if the leak is from a radiator, this may sometimes be the result of a loose joint, so if you notice that water is leaking from a pipe joint, use a cloth to dry the area and tighten the joint if you’re comfortable doing so. 

However, it is always best to leave any repairs to the professionals to avoid causing further damage. 

Frequently asked questions

So, is a leaking boiler dangerous? The answer will depend on the reason for the leak; however, in most cases, a boiler leaking water is not a good sign and should be looked at by a Gas Safe engineer.

A leaking boiler will require urgent attention as it can become extremely dangerous if left alone. It can result in structural damage to your house, is harmful to your health, and has the potential to explode in severe circumstances.

Although you can take some quick steps to prevent further damage if your boiler is leaking, you should contact a qualified engineer who has the right knowledge to either fix the problem or recommend a replacement.

Please check out this guide for everything you need to know about emergency boiler repairs.

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