Is your boiler leaking brown water? Here we explore common causes and solutions to fix it asap.
A boiler leaking is worrying enough but if you see discoloured water dripping out of it this can be particularly alarming.
But what causes a boiler to leak brown water? Rust? Dirt?...
And what can be done about it? In this guide, we’ll answer these important questions and explore other related sub-topics.
Let’s begin!
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Why is my Boiler Leaking Brown Water?
Note: If your boiler is leaking any water, whether discoloured or not, it should have locked itself out for safety reasons.
There are two components to a boiler leaking brown water; the initial discolouration of water in your heating system and the leak itself.
In other words, the two issues aren’t necessarily linked.
More than likely, the water inside your heating system had already discoloured and your boiler has likely experienced a leak around the same time, hence why you see brown water leaking from it.
Naturally, there are various reasons why a boiler may leak, however, there are only two common explanations for the water within your heating system turning brown.
It’s worth considering that the combination of causes is also numerous.
Be sure to have a professional verify the diagnosis you might have in mind. Of course, you’ll need to hire one to fix the problem anyway.
Causes of a Leaking Boiler
Before we consider why water coming from a boiler would be discoloured, let’s discuss the potential explanations for a boiler experiencing a leak.
These explanations can apply regardless of whether the water is discoloured or not.
Firstly, if your boiler is leaking from underneath then the culprit is likely poorly installed pipework or corroded pipework with the latter being the most likely explanation.
Another reason for a boiler leak is if the water pressure is too high.
While boilers are more likely to experience low water pressure, it is possible for the water pressure to get too high.
This can result in the pressure release valve discharging excess water or, if some parts fail internally, a leak can occur.
If your boiler’s pressure gauge is in working order it should make it clear whether or not the pressure is too high.
Usually, boiler pressure should be between 1 and 2 bars, however, you’ll want to double-check with the manufacturer’s instructions as to what the okay range is for your specific boiler.
Please be aware that even if the pressure gauge suggests that your boiler pressure is fine (or low), it’s always possible that it’s faulty.
More than likely, it will not be faulty but it’s important to be aware of all possibilities.
Other possible explanations of a boiler leak include corrosion to your system and general wear and tear.
Also, there may instead be faulty or leaky heat exchangers or perhaps even leaks from seals on internal boiler parts.
For either of these scenarios, you won’t be able to do anything DIY to get a clearer sense of what the exact problem is.
Whatever the case, if you’re unsure as to the cause, verify with a heating engineer.
After all, you’ll have to hire one to fix the boiler leak either way as it is not a DIY-friendly job.
Causes of Discoloured Water in Boiler/Heating System
Brown water within a boiler/heating system is indicative of there being heating sludge in the system.
Heating sludge emerges as an accumulation of rust and dirt inside the pipework.
As it builds over time, it will impact your heating system’s energy efficiency. Moreover, heating sludge can also result in blockages and damage.
In essence, if there is heating sludge inside your system it can discolour the water, causing it to turn brown.
With that being said, it’s also possible that a faulty hot water cylinder explains why the water in your boiler and heating system has turned brown.
This can happen when rust within a faulty hot water cylinder discolours the water, resulting in it turning brown.
One way of being more confident that heating sludge is the reason for discoloured water is if you notice that radiators aren’t heating up as they should be or/and have cold spots.
However, if in any doubt, you can always have a heating engineer determine the definitive cause.
After all, they’ll be required to fix it either way (more on that in the next section).
Fixing a Boiler Leaking Brown Water
Note: Again, unfortunately, none of these fixes is DIY-friendly. You must hire a professional for any and all of these potential fixes.
As touched on, fixing a boiler that is leaking brown water is a two-part process.
First, the leak must be dealt with and then the water discolouration will need addressing. Let’s explore the potential solutions to each problem separately.
Repairing the Boiler Leak
Note: If it is an emergency (regardless of the cause), you should contact your water supplier or (if available) a local heating engineer’s emergency contact number.
Let’s start by imagining that the cause of the leak is poorly installed or corroded pipework with the leaking coming from underneath your boiler.
While you may want to place a bowl or bucket beneath the boiler to collect the water that is gathering, you must hire a professional to fix this issue.
Also, if it’s quite a large leak, a bucket or bowl may not suffice.
If your boiler’s water pressure is too high, while you have to hire a professional to fix the leak, bleeding your radiators should help minimise the leak in the meantime.
For more information, check out our ‘How to Bleed a Radiator’ guide. If in any doubt, hire a professional.
You should do the same if you have concerns that adjusting your radiators could worsen the leak.
As for a case where your boiler is experiencing corrosion or there is general system wear and tear, you’ll also need to hire a professional to fix the leak.
Without opening your boiler up (this is not safe to undertake DIY), you can visually inspect any exposed pipework at your boiler for signs of corrosion.
Finding corrosion may help give you a clearer idea that this is the source of the problem and potentially along with wear and tear.
If your boiler’s heat exchanger is leaky or faulty, you’ll need to have a heating engineer either repair the heat exchanger or perhaps replace your boiler.
This is because if a heat exchanger cannot be repaired (as may very well prove the case), it means your boiler is probably beyond economical repair.
After all, having a heat exchanger replaced would probably set you back about £500.
Unless it is a relatively new boiler, if your heat exchanger needs replacing, you're probably best off having the entire boiler replaced.
While a new boiler installation can be daunting from a cost perspective, it is possible to purchase one on finance (with zero-interest options existing).
Last but not least, if internal boiler parts have leaking seals, you’ll again have to get a heating engineer to take a look and make the necessary repairs or perform some replacement work.
Depending on the extent of the damage, it’s possible that your boiler will need replacing.
Fixing the Water Discolouration
Moving on to solving water discolouration, if heating sludge is the cause then a heating engineer must perform a power flush.
This will rid your boiler of the sludge and fix the water discolouration.
Power flushing involves having chemicals added to your heating system at high pressure.
This dissolves the heating sludge accumulation while also flushing through contaminated water.
If instead of heating sludge (or in addition to heating sludge), a faulty water heater is at play, you’ll also need to have that repaired or replaced.
Nonetheless, even if there is no heating sludge but only a faulty water heater, a power flush will still be required.
Cost of Hiring a Professional to Fix a Boiler Leaking Brown Water
The average labour cost of hiring a heating engineer in the UK is £30 to £60 per hour. Labour prices differ across the UK from region to region.
To provide some contrasting examples, while labour fees are relatively high in London (£57 per hour) and Wycombe (£55 per hour), rates tend to be below the UK average in cities such as Cardiff (£35 per hour) and Manchester (£39 per hour).
Along with the price of labour, the total cost of having a boiler leaking with brown water fixed will also include the cost of supplies.
These are the average costs of hiring a heating engineer to fix a boiler leaking brown water:
Fixing a boiler leak of various kinds - £100 to £500
Replacing a faulty heat exchanger - £460 to £840
Bleeding 5-10 radiators - £30 to £120 *
Bleeding 10-15 radiators - £60 to £180 *
Power flushing your boiler - £400 to £800
Fixing or replacing a faulty hot water cylinder - £250 to £1,000 ^
Replacing a boiler if needed or deemed logical economically - £800 to £2,800
*If your boiler’s water pressure is too high, along with having the leak fixed, you’ll also need to have radiators bled in order to get your boiler’s water pressure down to a normal level.
^The cost of a hot water cylinder replacement can vary widely. If it only costs a few hundred pounds then it may be worth having it replaced and sticking with your current boiler (especially if the boiler is not that old). However, if it’s going to cost you £500 or more, you’re probably best off having your boiler replaced.
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