Water Dripping from Boiler

How to Fix a Boiler Leaking Water from Bottom

Water Dripping from Boiler: How to Fix a Boiler Leaking Water from Bottom

When it comes to heating, you should never ignore water dripping from the bottom of your boiler as it is usually indicative of a leak somewhere.

What’s causing my boiler to drip water?

When it comes to your boiler and heating system, you should never ignore water dripping from the boiler as it is usually indicative of a leak somewhere. While it could be a quick fix, it could indicate something much more serious.

What do you need to do? Follow our instructions and remember if you are in doubt, simply give PHS a call and if you’re in Suffolk or any of the Home Counties (Hertfordshire, Kent, London, Essex) we will be able to get an engineer to you in 24 hours.

How do I locate the boiler water leak?

How do you find where the water is coming out of the boiler and why can it be more of a challenge than you expect?

With boilers, it isn’t as simple as looking at where the water drips from. Pipes and gravity make it easy for water to look like its coming from somewhere else when in actual fact, it’s coming from somewhere else.

Usually, if water is dripping anywhere around your boiler, the leak will be internal and we don’t recommend you take your boiler apart to locate the source of the leak.

A Gas Safe registered heating engineer will be your safest and quickest bet to locating the leak without causing yourself any further problems.

Is this going to cost me a lot of money?

This totally depends on the severity of your leak and what part needs repairing. Worst case scenario, you may need to replace your boiler.

Is a leaking boiler dangerous?

Long story short, yes.

If for example, it is one of the causes below, such as pressure, it could (if left unattended) mean your boiler’s pressure gets dangerously high. It’s best to be safe rather than sorry, especially when it comes to something like your heating.

What’s the likely cause of a boiler leaking water from the bottom?

Even though we cannot promise any of these are the answer you’re looking for and we recommend you get one of PHS’ Gas Safe registered engineers on the scene, this could help guide you in your search for answers.

Here are 7 of the most likely suggestions, and we’ve put them in order of severity for you.


You must always keep an eye on your boiler pressure and ensuring it is between 1 and 2 bars is a good place to start!

When the pressure is too high, your boiler could struggle and subsequently force some of the pressure out via the pressure valves. It is designed to do this and it’s normal too.

The valves leak occasionally to prevent your boiler exploding the moment the pressure rises, but this doesn’t mean you should let the pressure go over 2 bar regularly.

The amount of water you find being released in this way will indicate how much excess pressure your boiler has.

Try to reduce the pressure and see if your boiler stops leaking water from bottom.

Loose Joints

If you suspect the source of the water is coming from a loose joint, it is quite easy to fix, and more common than you’d expect.

This is because as the seasons change and the use of your boiler fluctuates, your assets have to adjust to a lot of hot and cold changes, shifts and expansions.

Try to look at all the pipes coming out of the system and see if you can track the water back to a particular joint, which you can tighten. Make sure to check the element isn’t damaged.


Temperature valves dispel water when the water is too hot. There could be a fault with the heating system which is heating up the water above the level needed.

Check for a fault code and look at replacing the system’s temperature reading device/internal thermometer/temperature probe.


If any seals are damaged around your boiler, it will allow water to leak out.

Replace seals and potentially the pump also, if the pump is responsible for pushing the water out.

Human Error

When it comes to the installation of a boiler, quality is always key. That’s why we ensure our engineers are of the highest standard to avoid any faults post-installation, leaving our customers happy for a long time to come.

If you used an installer/engineer and not long after your boiler develops a leak, it is likely that the engineer employed to do the job did not do it to the sufficient standard.

From not quite fitting the pipes properly to not using the highest quality parts and tools, it isn’t worth the hassle to employ someone who isn’t trusted to do your boiler.


This is one of the most common causes and it can be a simple fix but it can also be a big cost to the average homeowner.

In some cases, corrosion can be tracked to a particular element in your heating system and perhaps its condition is clearly deteriorating. In this case, you can replace the part at a reasonably low cost.

Unfortunately, there can be a bigger issue, if the corrosion is severe and in several places (or worst case – across the entire system). This will require an extensive repair or potentially a new system.

Boiler body condition

In older boilers it is very common to find that the years’ of use and expansion and contracting that the very nature of boilers have to go through can begin to tire your system’s body, slowly causing cracks.

While a crack won’t be difficult to spot it does indicate a serious problem.

If a crack is causing a leak, it is likely that your boiler has come to the end of its life and it’s time to get a new one.

Recommended reading: What Should Boiler Pressure Be When Heating Is On?

Why is my boiler leaking water from underneath? Your next steps

At PHS we want to ensure we cover everything, so if you aren’t sure about the source of the drips – call an engineer today so we can do thorough checks.

If you spot a leak or a drip, the quicker you act, the better!

Your system will become more damaged if you ignore it, in nearly every case stated above and you want to ensure you use a quality engineer, to keep your home warm and running safely for years to come.