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10 Water Leak Causes Detailed – Top Ones

Water Leak Causes

What are the Main Water Leak Causes?

We have a lot of experience in dealing with water leaks of all kinds, we have seen many thousands of them but we often get asked the top water leak causes, well here we go!…

Well to start with, dripping taps are a very common cause of water leaks but, given the water usually drips into the sink and it is easily fixed, they rarely cause water damage.

So what are the most common water leak causes in your property?

1 – Frozen Water Pipes

As you might expect, this is seasonal, happening much more in winter months (especially December to February) but freezing temperatures can clearly cause water in pipes to turn to ice. As you will likely know, water expands as it freezes and so this puts pressure on pipework and can cause it to split.

This picture below is of a leak from a copper pipe from freezing….

Frozen Copper Pipe Split

As you can see, it is a fairly dramatic split which, when the water thaws, leaks a very large amount of water. Not all splits are this big but frozen pipes are one of the most common water leak causes. Often, after a cold snap (such as when the UK experiences ‘Beast from the East’ cold weather) there are a lot of water leaks. Often this is in a hidden place which is when people contact us for help.

We have a separate guide on frozen water pipes too.

2 – Cold Water Tank Failure

Cold water tanks are often found in the loft of properties and loft tank leaks are one of the most common water leak causes. Clearly the mechanism in the tank is designed to draw water to refill the tank after usage.

However, over time and from regular use, they can start to fail and in some instances this can mean that the water runs constantly, or the connections to and from them can fail causing water to leak

The problem with cold water tank leaks is three-fold;

  • Because tanks are often in the loft, people tend not to notice (see or hear) the problem
  • The leak can be catastrophic (fast) and damage multiple rooms below. Even a slow leak, over time, can cause damage ‘behind the scenes’ in properties. And related to that…
  • The water can travel down to other rooms through gaps, cracks and voids in properties (horizontally and vertically!) so that people might see a damp patch downstairs and sometimes think the leak is there when in actual fact it is from the loft.

Often this type of water leak can require Water Damage Restoration work afterwards. Water Tanks are on our separate list of things that hold and leak water in your home if damaged.

3 – Corroded or Cracked Copper Pipes

Copper pipes are obviously very common for both hot and cold water pipes in properties. Consequently they are one of the most common water leak causes

Although it is not one of the most reactive metals, over time (and especially in certain conditions) copper pipes can become damaged through corrosion or other means. This can be a significant leak or, very often, a slow leak which is harder to find. Leak detection experts have various tools and methods to find leaks in copper pipes, even very small leaks or leaks that are in concrete slabs.

There is a phenomenon in copper pipes called ‘pepper potting’ where very small holes appear in a pipe (most often in underground water pipe leaks) causing damage. Like the lid of a pepper pot!

4 – Broken Pipe Connections

This area covers a lot of things where either one pipe is connected to another (which can be, for example, copper to copper or copper to push fit connection) or where a pipe is connected to something else. One of the most common water leak causes is from connections to washing machines or dishwashers. We deal with a lot of washing machine leaks and dishwasher leaks!

Sometimes people find out that they have a soft or ‘spongy’ floor in their kitchen or utility room (one of our top 10 signs of a water leak). They know that their washing machine or dishwasher is not leaking fast because they cannot see standing water. But a slow dripping leak can, over time, absorb into floorboards etc and spread across a floor causing structural issues as well as mould, including black mould.

These types of water leak causes are commonly from poor or incorrect fitting, loosening over time from use, things like washers or connectors perishing over time or just poor workmanship. Always be careful after a new device has been connected and watch to see if there is a leak.

The picture below is from a water leak we managed to find quickly at a property, before it caused too much damage to the floor…

washing machine water leak
Washing Machine Leak

You may find our article about how much water washing machines use, which also has useful comparisons with other household appliances such as dishwashers.

5 – Seals or Cracks around Baths, Showers & Sinks

As you might expect, we find a lot of water leak causes that are around baths, sinks or showers. This can be caused by various things but often its from a problem with a seal around them (often silicone) breaking down over time, from a connection / pipe or even from a hairline crack (which are hard to see).

For more on this, a good example is a shower leaking through ceilings, which as you will see can be caused by several things (including a Shower Drain Leak) and cause a lot of ceiling water damage.

As we said above with other slow leaks, this can go unnoticed for a long time. The water can absorb into the structure surrounding it (wood, plaster or concrete) and largely go unseen for a while.

We use various methods to find this type of water leak, just one of which is thermal imaging which can highlight things that the naked eye cannot see.

6 – Central Heating Leaks

We have an entire page dedicated to central heating leaks so as you might expect it is one of the common water leak causes. Central heating pipe leaks can be very hard to find because…

  • Often the leaks are very small / slow – building up over time
  • The pipework in central heating systems are often in walls, under floors or even in concrete
  • If there are visible signs of a leak, they may not necessarily be directly where the leak is
  • Opposite to that, there may be no visible sign of a leak – for example you might just have an error code on your boiler saying you have a problem with pressure dropping
  • Of course, the things above can be combined

However, a leak detection specialist will be trained to spot these things, have specialist tools and equipment and give you a much better chance of finding your water leak causes.

So if you have a problem with your central heating leaking – contact us for help today

7 – Broken Waste Pipes

When people think about common water leak causes, many immediately thing about hot or cold water pipes. However, waste water pipes can be common too. Waste water can bring its own challenges because it can involve things such as sewerage waste pipe leaks which have an increased risk of bacteria / microbial activity. Its also just unpleasant, especially of there is an odour involved.

All our leak detection engineers are also trained in water damage management and will carry specialist antimicrobial and odour control solutions to help mitigate the risks from such leaks.

This area of water leak causes is obviously linked to some of the other top 10 things mentioned – for example, like number 4 above, a connection from a toilet to a soil pipe can be a source of a toilet leak.

In fact, this image below is from exactly that kind of leak where water damage was seen on a wall and ceiling below a bathroom leak

Leak in Ceiling
Leak in Ceiling from Toilet Above

Looking where the hole is you can see copper and push fit plastic pipes in the vicinity of the leak. You might think that it is one of those leaking that caused the problem but, in actual fact, it was a leak from the connection from the toilet to the soil pipe. Every time it was flushed a small amount leaked.

As you might expect, finding these leaks quickly is important so if you think you might have a waste or sewer pipe leak get in touch with us today.

Water Leak Detection Service
Water Leak Detection Service

8 – Expansion from Heat

Much like some of the other examples, especially number 1 of the water leak causes on this list, one of the main water leak causes is from temperature changes. We mentioned freezing pipes earlier but equally, hot temperatures can cause water leaks too. Like many things, water pipes and connections expand and contract with heat changes. When something warms up, it can expand, causing movement which in turn can cause a water leak. People often associate water leaks as a winter thing but they happen all year round, even in summer months.

Clearly this applies to hot water pipes, especially in central heating systems. We’re sure many of you are familiar with the clicking or knocking sounds of hot water pipes as they warm up, this is caused by expansion movements, often rubbing against other materials.

This expansion can cause a water leak but also, they can cause an existing weakness or beginnings of a crack etc to worsen causing a leak, hence they are common water leak causes.

9 – High Water Pressure

Very similar to number 8 on our water leak causes list in many respects is problems from high water pressure. This is one of the more common water leak causes. This is because higher water pressure can put more strain on pipework, and like the previous point, expose or exacerbate existing issues, potentially causing a water leak.

It’s important to say that changes in water pressure are not necessarily something to be too worried about as well fitted and maintained water systems are designed to cope with water pressure above standard levels. In fact, many of them have systems within them to deal with that exact situation.

That said, if you are experiencing much lower water pressure than normal you may have a water leak. We talk about this more on this page about signs of a water leak (number 9) and…

Elsewhere, we discuss water pressure it in your home and water flow meters.

10 – Storm / Weather Damage – Ingress

In some situations water leak causes are not caused by water within the property escaping from internal pipes, they can be from external water entering the property.

There is a long list of things this can include…

  • Storm damage
  • A roof leak
  • Ground water
  • External water leaks entering a property
  • Rising damp
  • Gutters overflowing
  • Cracks in walls (brick or render etc)
  • Gaps in or broken seals on doors or windows
  • The list goes on!

This is a whole other area of water leak causes and potentially more complex because…

A bit like trace and access cover on your home insurance, you will need to check if you are covered for these things but we can help with those discussions. You may also need to check with your insurer.

As experts in water damage repairs, we can help if you are affected by any of the above. Our friendly, professional and reliable team will be glad to help you.

Water Leak Cause Various
Water Leak Causes Various Sources

Finally, here is a bonus section on water leak causes…

Accidental Damage

Like number 10 on the water leak causes list we collated above (a) this covers a lot of things and (b) it may or may not be something you are covered for on your insurance.

However, irrespective of that, another area of water leak causes is accidental damage! Water leaks sometimes don’t happen for no reason, they can be caused by people and it may not be immediately obvious. There are various example of this, some of which would not really be classed as a water leak, including the first on the list…

We could go on but you get the point! You might think that some of these would cause a water leak immediately but that is not always the case. Take the last one for example, we have seen situations where people have, for example, had a kitchen fitted years ago and accidentally screwed through a pipe which leaked slowly for many years.

  1. Leaving the tap running in a bath or sink
  2. Banging or knocking a pipe or something connected to a pipe
  3. Breaking something outright, like from leaking on a water cistern (we have seen it!)
  4. Spillage of water (anything from a cup to a bucket of water)
  5. Breaking a water tap
  6. Cracking a bath, sink, toilet or shower tray
  7. Putting a nail or screw into a water pipe when doing DIY

Hopefully you found this article on common water leak causes interesting. As we always say, if you think you have a water leak or spot something that might indicate a water leak, get in touch.

We have a shorter version of this article on places to find water leak in houses too. is brought to you by Rainbow Restoration, are leading experts in Disaster Recovery and Restoration – trusted by many of the top insurance companies.

Rainbow International Small Logo
Rainbow Restoration (formerly known as Rainbow International)

Who is responsible for Water Leaks outside?

We have a really useful diagram on our page about reporting water leaks that will help you to understand if it is your responsibility or your water company. We also explain who to report them to and how. However, in many cases if an outside water leak is on your land, then you are responsible. Beyond your property, is usually the responsibility of your water company for mains water leaks.

What does a water leak sound like?

The sound a water leak makes will vary on the type of water leak you have. A drip sounds very different to a spray of water. We have more on this in our guide to acoustic water leak detection and acoustic listening devices. If you hear the sound of a water leak in an unusual location, especially if it is new or is accompanied by damp, get it checked out as soon as possible.