Water in Your Basement: What Caused It, What to Do, and How to Stop It

Flooded basement

February 11, 2022

If your property has a basement, then you know how crucial it is to keep that space dry – and just how damaging it can be if water does find its way within.

So, if you have found water in your basement then we are sure that there are plenty of questions in your head about what to do when you find water in your basement, what the cause of that water might have been, and of course what you can do to avoid the same thing from happening again in the future.

What to Do if You Find Water in Your Basement

If you discover water in your basement your first instinct might be to panic – or just to try and bail as much water and dry out your basement as fast as possible. Really though you should try and keep a clear head, and run through the following checklist.

Make Sure That Your Basement Is Safe:

Any amount of water in a basement means that the basement itself is compromised. This could be in a big way, or just a small one; but its important that even before you enter your basement you make sure that the room itself is safe to be in.

That doesn’t just mean the walls and structural support either. Make sure that power to the basement itself has been turned off, as any loose or frayed wires could well be catastrophic and dangerous if they are submerged, or even laying in the basement water.

So, if you are headed into a basement and there is any level of flood apparent, it may well be wise to wear grounded rubber boots (like a pair of wellies) just to make sure that any electrical current not stopped by shutting off the power doesn’t do any damage to you immediately.

Of course, it would be very wise to avoid touching any electrical objects or wires until a professional has visited and inspected your basement, making sure it’s safe, or before you can be certain that all of your electrics have been turned off.

Figure Out Where the Water Has Come From, or Is Coming From

The water in your basement will not have magically appeared there – there is going to be a reason that your basement has become flooded.

So, you will have to find out just how that water got into your basement. If there has been flooding in your area due to inclement weather, then it should be fairly obvious that this is the cause of the water in your basement.

Usually if the water is from the likes of a nearby overflowing river or other one off causes of flooding the water itself will be dirty, full of debris and generally quite unhygienic.

If the water ingress is the result of a continuous leak then it could well be a little longer before you notice the water has built up in your basement to a stage at which it could be called a flood. This is especially true if you tend to not spend time in your basement and there has been no dramatic flooding in your area. Even if there is only light rainfall a basement can still be vulnerable to leaks and floods.

So, on discovery of your flood, try to discover the cause of the flood itself. Remember, if there is heavy rain and known flooding in your area then it may well be unsafe or a wasted effort to try and combat the flooding until the flood waters have subsided.

The same may apply to continuous leaks that have sprung in your property, especially if those leaks are the results of a deeper problem within your walls. You may find that damp is a major contributing factor in your flooded basement, or that the flooding is the result of a larger underlying problem.

Either way, the leaking water will still be a problem until those larger underlying issues are resolved.

Remove the Standing Water as Soon as Possible

Getting rid of any standing water in your basement after a flood should be a priority. This can be done in a number of different ways, depending on the actual amount of water that has collected in the basement.

You could use a hand pump and a pipe to clear out the water if the amount collected in your basement seems manageable to do by hand – or you could look into using a wet-vac for smaller amounts.

For larger amounts of water you can always look into the use of an electric pump – but the matter remains that you need to clear any standing water as quickly as possible, due to the danger posed by bacteria that dwells in the water, and the significant risk it poses to your buildings structural integrity.

Inspect, Save, or Dispose of Affected items

If you have been affected by a flood within your basement, then it’s a pretty easy assumption to make that some items will have been in contact with the flood water.

Make sure that you take any of these damaged items out of your basement, and attempt to dry them as best you can. The reason for this is twofold: the first being that you will obviously want to save what furniture you can, but also because wet items (especially furniture) will attract black mould if they are allowed to stay wet for too long.

Throw away whatever is beyond repair, but if your property can be dried out then make every effort to do so – but once it is dry, you may need to look into professional cleaning services, or potentially reupholstering depending on the extent of the problem.

Once your basement has been dried, cleaned, and treated though, you are going to want to take steps to avoid any of this happening again. What can you do to make sure you don’t suffer another basement leak though?

Why Is There Water in Your Basement?

Water can enter your basement for a number of different reasons, and each of them should be treated with the same amount of seriousness and importance, as any kind of leak or water ingress can get progressively worse over time and cause further structural, water, and cosmetic damage to the property itself.

So, what are the different causes of water in a basement?

Lateral Pressure

Lateral pressure is a process through which a lot of leaks are created in basements, and many property owners don’t realise that what could have been easily avoided early in the stages of lateral pressure has led to a significant leak.

Lateral pressure is the name for when the soil surrounding your properties below ground structure’s walls (your basement or cellar’s exterior walls) absorbs water, which naturally makes it expand. This expansion in the soil will cause that same soil to press against the exterior walls of the basement, and over time (and with heavier rainfall) that force can translate into a breach being made in your basement walls.

This new crack will provide a ready way for that same moisture that created the lateral pressure to drain and leak through into your basement walls, potentially causing the crack to grow in size, more water in the basement itself, and further damage to your basements walls.

Lateral pressure is hard to predict as you have no real way of knowing if your basement is surrounded by ground that will be prone to lateral pressure – however, if you happen to notice that a crack has appeared on one of your basements walls then it is always important to get it checked out as quickly as possible to avoid greater damage and the possibility of a future flood.


Condensation may well be the main cause that water has been building up in your basement – or the reason that cracks form, allowing further water in.

Condensation is pretty simple. When humidity is made in rooms that don’t have adequate ventilation, that same humidity easily transfers onto the surfaces in the room itself. This can mean windows, walls – even furniture, but the end result is always the same: moist walls.

Moist walls leads to two things. The first is black mould, and this on its own isn’t good as it comes with a host of both physical health and property damaging traits. Secondly, condensation (if frequent) can lead to damp setting in a wall – which can damage a wall to the point that it crumbles.

This means that in a basement you could find that the condensation based damp could combine with lateral or hydrostatic pressure to create a new crack or larger hole in your wall – which of course means that water is going to have a much easier time making its way in.

Condensation is easily made, so if you have a basement or cellar you spend a lot of time in, or that is prone to moist warm air (like if there is a dryer down in the basement that you use frequently), then you should definitely keep an eye on your basement’s condensation levels.

Hydrostatic Pressure

Hydrostatic pressure is similar to lateral pressure, but instead of the moisture soaking into the soil, the moisture soaks directly into walls.

Obviously, this can lead to quite dramatic and destructive consequences. Any amount of moisture within your walls is going to be cause for concern, as even the slightest leak can allow for water to pool in your basement over time, and of course, allow more water in your walls.

More water in your walls means a steady expansion of damp, the weakening of the building materials making up the walls themselves, and consequentially, the eroding and expansion of that original leak.

So, whilst you might only have a small leak due to hydrostatic pressure to begin with, you can expect it to expand and get worse as time goes by. You may also notice that during warmer or drier periods the leaks in your walls go away. That’s because there is less moisture in the soil itself to transfer into your walls.

Once the rain starts falling and the temperature drops however, any moisture in the soil is going to build up, and over time expand the soil to pile pressure onto your below ground structures walls. This is what is known as lateral pressure, and if left untreated it can cause some serious issues within your basement.

Mechanical or Waterproofing Failure

You might be confused seeing mechanical failure as one of the reasons that your basement might suffer from a leak, but if your basement has already had some kind of waterproofing system installed then it’s actually a very common reason for water appearing in your basement.

First, lets address waterproofing failing your basement following it’s installation. For example, if your basement currently has a Type A waterproofing system (or tanking, as it’s known), then your basement walls are going to be completely waterproof.

That means that water which in the past may have applied pressure to a specific area of your basement walls will now no longer be able to push through the walls where it once did – leading that same water to trickle and flow below ground to a different area of your wall, which (under greater pressure) could buckle under the pressure and give way to the water ingress.

Simply put, Type A waterproofing can easily disperse lateral or hydrostatic pressure, and cause it to break through your basement walls in areas where previously no problems at all – or where there were problems, but unknown to the owner as they weren’t severe enough to notice.

Then there is the much more likely scenario in which a basement begins retaining water due to a faulty or broken sump pump. The sump pump is a vital part of any Type C waterproofing system, and is responsible for collecting and pumping away all water that manages to leak into the basement itself.

There are plenty of reasons that a sump pump might fail, and any one of them can be enough to compromise your entire basement waterproofing system. If your sump pump’s float switch breaks for example, then your sump pump will have no way at all of knowing when to empty itself, and consequently could easily overflow, allowing water to pool and spread through your basement.

Circumstances Beyond Your Control

Sometimes basement and cellar leaks aren’t a product of basement construction materials failing, or the breakdown of a sump pump. Sometimes, rivers burst their banks, or drains back up, or widespread flooding takes place.

These are pretty unavoidable circumstances, and the sad fact is that they do happen. When they do occur, we are pretty sure that you are going to be aware, so any damage that is done by flooding in these situations is going to be reacted to quickly and effectively.

If you are the victim of flooding from something like a burst river bank or backing up sewers, then its best to get in touch with the local authorities and reputable experts about the next steps you should take, as they will have the most current information regarding safety and progress for your property.

How to Stop Water From Entering Your Basement Again

If you have discovered water in your basement it’s going to be a high priority for you to make sure that it doesn’t happen again. However, deciding what steps to take depends entirely on the cause of water leak in the first place.

How to Stop Lateral Pressure Causing Basement Leaks?

If your basement has been subjected to leaks because of lateral pressure then its likely that you won’t have the skills to remedy the lateral pressure alone (unless you are a qualified waterproofing engineer).

So, on discovery of bowed, leaking or cracked walls in your basement it would be advisable to contact a basement waterproofing specialist for a comprehensive waterproofing survey.

In most instances the surveyor will assess the ground surrounding your property to ascertain the likelihood of lateral pressure being the cause of the leak, and suggest what can be done to minimise this risk if it is in fact at fault.

Then, general repair work will be advised for the at risk wall itself before a cavity drainage waterproofing system is installed in conjunction with a sump pump to best manage any water ingress, and keep your actual basement dry even if the lateral pressure cannot be stopped.

A cavity drainage system, or Type C waterproofing, is a method of waterproofing that relies on waterproof membranes fixed to the walls and floor of a basement to capture and channel any water entering your basement, and direct it through drainage channels into a sump pump, which in turn collects the water and pumps it away from your property.

Plasterboard can be applied on top of the membranes themselves so even when your basement is completely protected from water ingress via a Type C system, you can fully furnish and enjoy your basement entirely. Also, if you have a Type A waterproofing system (or tanking as its commonly known) in place, then cavity drainage waterproofing will be able to work entirely in conjunction with that system, more comprehensively protecting your basement.

Once that Type C system has been installed in a basement it will be up to the sump pump alone to keep your basement dry and secure, as any water leaks will be pumped away by the sump pump itself. As long as your Type C waterproofing system is kept well maintained, and the sump pump receives regular check-ups and maintenance then your basement will remain secure.

How to Stop Hydrostatic Pressure Causing Basement Leaks?

Hydrostatic pressure is dealt with in much the same way as lateral pressure – following a survey that finds hydrostatic pressure as the main cause of the water in your basement, you will want to take any advice the surveyor has on treating the ground around your property to combat hydrostatic pressure.

Following that, you will probably get recommended a Type C Waterproofing system for your basement; a cavity drainage membrane system with the requisite sump pump to keep your below ground structure protected around the clock.

As hydrostatic pressure is something that is intensely hard to either rectify or stop completely without the implementation of serious groundwork to stop water flowing below ground towards your basement wall, a cavity drainage system protects your basement in another way.

The water will still make its way through your wall – however, instead of collecting on your basement floor, the water will instead be collected by the cavity drainage system, and funnelled towards the sump pump before it is ever noticed by any occupant.

As long as your cavity drainage system is well maintained, and your sump pump receives the kind of attention it needs to keep it in full working order, your basement will be protected against the kind of water ingress associated with hydrostatic pressure.

How to Stop Flooding or Other Events Out of Your Control Flooding Your Basement

It’s pretty hard to predict when, or if, your basement is going to flood because of natural causes. Maybe if your property is sat below the water table, or if you reside within a well known flood area then you might already have an idea on the likelihood of your property flooding.

However, realistically, it’s nearly impossible to predict when your home will flood due to environmental factors. The best you can do is make sure that any flood defences or barriers you might have in place if your property is in a known flood risk area are up to scratch, and that all flood protection your basement employs comply with regulations

You may also want to consult our guide on what to do if your basement is at risk of suffering a leak during a power outage. If you make use of a sump pump for example then you may be more protected than you think, as sump pumps can work on an independent battery source away from the power supply of your home.

Make sure that you are ready to react in the event of extreme flooding, and make the most of the resources you have to minimise the risk of any flooding that might occur.

How to Stop Mechanical and Waterproofing Failures Causing Basement Leaks?

Firstly, the waterproofing failure. Usually, the most common types of waterproofing to fail are Type A and Type B waterproofing systems. This is because they are installed either during the initial construction of the property itself, or are applied to the exterior of the property – which is of course, below ground.

So, in the event that a Type A or Type B waterproofing system is compromised, you will be happy to learn that a Type C waterproofing system can easily be applied to the interior of your basement to work in conjunction with any pre-existing waterproofing system in place.

This means that any water that makes its way through the tanking or waterproof building materials in your basement will be collected by the Type C cavity membrane, meaning it never actually sees the interior of your basement.

Speaking of Type C waterproofing then, how can you stop mechanical failure from causing water to appear in your basement? It’s simple enough; with a comprehensive maintenance schedule arranged with a specialised engineer who is capable to check your below ground waterproofing regularly, to spot any mechanical issues in your sump pump that could potentially lead to failure, and leaks.

Mechanical failures in a basement generally relate to pumps – either sump, or sewage pumps specifically. A visit by a qualified engineer who is trained in spotting potential problems in the pump that could lead to breakdown every few months can easily avert disaster, especially in the months leading up to the wetter seasons of the year.

Broken float switches, clogged discharge pipes, burned out motors – all of these and more are reasons that a pump might break, and whilst they can be fixed if they were to break, it’s always easier to prevent than it would be to remedy.

To arrange a maintenance schedule that works for you, get in touch with our team on 0800 019 9949, or contact us online today to see how we can help you keep your basement dry.


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