Why is Water Leaking into Basement After Heavy Rain? | 8 Top Reasons

Having water leaking into basements after heavy rain is not uncommon in the UK and it can be both a challenging issue to deal with and potentially distressing for homeowners and businesses.

In this article, as leak detection professionals, we will explore and explain some of the common reasons for water leaking into basements, explaining each one step by step.

Understanding Basement Water Issues

Basement are especially vulnerable to water ingress issues, especially after periods of heavy rainfall, when water quantities can be both higher and accumulating around the property. Especially if there is flash flooding too.

This can lead to a flooded basement. As basements in their nature are below ground level, water leaking in can be high risk. In fact it can be a common enough problem for specific properties but there is a requirement for a sump pump to be installed.

Common Causes of Water in Your Basement after Heavy Rain

We will now briefly list eight of the most common causes for water accumulating in your basement after heavy rain (many of these are related to each other):

1. Drainage Issues – when there is persistent and heavy rain this can overload drainage from properties and around the area, causing drains to ‘back up’ (meaning water intended to leave the property is returning back in) this can be especially a problem with old or damaged drains.
2. A High Water Table – after periods of heavy rain, the ground can struggle to drain water away leading to localised increases in water table levels. This level of increased moisture in the ground can both (a) lead to additional structural pressure on properties and (b) worsen or expose any structural weaknesses. Which leads us on to our next one on the list.
3. Cracks in Structural Basement Walls – another place that water can leak into basements after heavy rain is via cracks in basement walls or adjoining walls. Leading on from the previous point, the increased water levels are looking for the path of least resistance which may be into your property. This may bring some of the outside contaminants with it, what is commonly known as ‘black water’.
4. Incorrect Grading around a Property – This is something which can worsen the effect of water leaking to basements after heavy rain. Poor grading around a property can lead to water channelling towards the structure and into basements in some instances. Ideally to prevent this better grading, or the measures, would be advantageous.
5. Ground Movement (leading to pipe leaks) – Sometimes when there is excessive moisture in the ground around properties the extra pressure and movement can lead to water pipes breaking or cracking, making the situation worse with the water leak. This could include exterior mains water leaks or internal water leaks.
6. Gutters and Downpipes – excessive rain can put additional pressure on gutters and down pipes on properties and a bit like we mentioned for drainage issues in (1) can expose or exacerbate issues with the integrity of these. Clearly if these break or are broken, it compromises their purpose – which is to help rain water flow away from the property. This too can leak to a water leaking into basements after heavy rain.
7. Broken Sump Pumps – As we mentioned earlier, sump pumps in basements are not uncommon in the UK and they help to extract undesirable excessive water from basements. Clearly if the pump is broken it cannot perform its designed function and so the rainwater will congregate rather than be extracted. This may indeed have been caused by excessive pressure put on the pump from the heavy rainfall. So if you have a sump pump in your property make sure it is regularly checked and maintained.
8. Localised Flooding – As you would expect flooding, including flash flooding is often more common after heavy rainfall. This loading can lead to elevated water levels outside and around properties which is at higher risk of ingression inside, including into property basements. One area is some from localised flooding, it is often the basements of properties that are hardest hit, leading to severe water damage.

In regard to 2 on the list, you can check local ground water levels on the GOV.UK website.

Signs of a Leak into Your Basement

If you have a property with a basement and have experienced recent heavy rainfall, especially over prolonged periods, we recommend that you check your basement for the signs of a water leak.

These signs can include:

• Damp patches on walls or floors (especially if they are new)
• Pooling of water in your basement after rainfall
• Signs of mould growth in your basement (mould likes damp conditions!)
• Musty / foul odours, which could come from mould or backed up drains
• Issues with water draining away from basement sinks, toilets or showers
• There are many other things to watch for, but these are some of the main ones

On top of what we have mentioned, places to be extra focused on can be looking for:

• Water leaking from chimneys into basements after rain
• Water leaking into basements from window wells
• Water leaking into basements from toilets and bathrooms

Identifying the Source of Water Leakage

Assuming that you have identified you have a water leaking into basements after heavy rain, the next challenge is identifying the source of the water leakage. In some instances this can be somewhat obvious, however on many occasions, it can be more challenging to identify the source. This is where trace and access experts such as ourselves, can help.

We are able to carry out a number of tests, using specialist equipment to check for water leaks and test the actual water to give greater clarity on the source. We are also experts in water damage management, which as you would expect is a very beneficial skill to have in this situation.

Solutions for Preventing Water Leaking into Basements after Heavy Rainfall

As you might expect the solutions to preventing water leaking into your basements after heavy rain are very much related to the causes we covered earlier in this guide. So for example, making sure your drains are in good working order, flowing correctly and maybe even get inspected from time to time can be very beneficial.

The same goes for checking the structure of your property especially in the basement, looking out for damage or cracks etc. Finally, keeping an eye on the exterior of your property, including the aforementioned grading, maintaining and clearing gutters and down pipes etc, will help to reduce risk.

However on top of that there are some additional measures that can be taken, these include:

• Sump pumps, as we have covered in this article
• Water leak alarms and sensors to indicate the presence of water
• Things Such as French drains can be beneficial to stop water pooling
• Check and maintain plumbing and watch out for things like water pressure falling
• Landscaping your garden may help with directing water away and drainage
• Get professional help if you have persistent problems

Finally, as we said earlier, be especially vigilant for issues with water leaking into your basement after periods of heavy rain. And on top of that, especially if the ground is already saturated from previous seasonal rainfall.

One thing we haven’t touched on here is basement waterproofing, which is where people have had their property protected from basement water ingress issues. Sometimes this is carried out at the point of the property was constructed, but other times it is a retrospective edition. Because each of those situations is unique, we did not covering it in this article but may do so in a separate guide.

Here are similar articles you might find interesting too, related to water leaking into basements:

• Shower Leaking Through My Ceiling
• Best Ways Of Finding Water Leaks
• Underground Water Leaks
• Slab Leak Detection
• Central Heating Leaks

Water Leaking into Basements – FAQs: