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What Are the Main Causes of Flooding in London?

Flooding in London

Flooding is, unfortunately, something that many of us will be thinking about more and more over the next few decades. Major flood events in the UK seem to have become a more regular occurrence, with 5 of the wettest month records coming in the last 20 years alone.

Since flooding can destroy homes and businesses, and with the Met Office predicting things will only get wetter and warmer as time goes on, we thought this would be a good time to discuss the main causes of flooding in London and how to help prevent damage to your property.

Let’s start by looking at some of the common causes of flooding in London:

Extreme rainfall

While the levels of rainfall in London are not even close to the amount seen by some parts of Scotland and other areas of the UK, it’s the extreme conditions that bring with them the highest risk when coupled with the Thames tide and other local rivers.

London is a densely packed city, so any prolonged rain or heavy flash storms can begin to cause problems across the region. In 2021, there were a number of events across the capital that sparked panic and caused millions of pounds worth of damage – including in Chelsea, Kensington and Notting Hill.

The most shocking scenes of last year, however, were shown in videos of Pudding Mill Lane station in East London that went viral when it was submerged by floodwater.


Poor drainage infrastructure

In addition to the Thames and other smaller rivers in London, the rainfall is made all the more dangerous because of the poor infrastructure in the city.

Since plenty of the city was designed with a combined sewer system decades ago, it is vulnerable to more modern levels of rainfall. A report published by London Assembly back in 2002 highlighted that Thames Water admitted: “there are areas where changes in use have put a strain on the drainage systems”.

So while the drainage systems in the city may have been designed to take on rainfall water, it seems they are still vulnerable to more severe conditions. And without the open land found in other areas of the UK to soak up excess rainwater, the majority of it will need to be diverted from the city by sewers and drains.


Blocked drains

Even if London’s drainage systems were modernised, there is still always the threat of blocked drains. It’s simple really: even a partially blocked drain cannot divert large quantities of water. Instead, it will back up with rainfall and put further strain on the surrounding system until those drains, too, become overwhelmed. 

Blockages can occur for all sorts of reasons, including foliage and other debris choking the entrance to storm grates, but one issue that has been across the headlines in recent decades are fatbergs. As recently as last year, engineers had to tackle a large blockage formed by oils, grease and other non-biodegradable items underground in Canary Wharf. 

These fatbergs have become all too common in London, putting greater pressure on drainage systems when heavy rainfall does arrive. It’s prompted calls for people to be more careful with what they put down their sinks and toilets


How to prevent flooding in Central London

With all of the above in mind, it’s never been more important to ensure that your drains are in good condition, dealing with blockages immediately. In delaying dealing with any potential blockages, you’re essentially increasing pressure on the system when it is required to handle both the water from your property as well as rain. This can lead to sinks and toilets backing up in your premises – something no homeowner or business wants.

In addition to drain unblocking, at 1st Call Drain Clearance & Technical Services, we also provide sump pumps for basements to help protect against floodwater in your property. Ideal for homes and businesses, they could be the difference between keeping your property dry or finding it in a state of ruin. They work to remove water from your property when triggered at a low level by flooding.

To find out more about our drainage services, submersible pumps and how to prevent flooding, simply contact our team today. We help homes and businesses across Central London, Harrow and Ealing and we’re always happy to help you with any drainage issues you might be experiencing. 

Problems with your drains?

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Areas We Cover

We have engineers covering London, Central London and the Home Counties


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