The presence of pumps in a flood defence scheme benefits everyone involved and the overall success of the scheme.
When people think of flood defences, they usually picture tall walls or sturdy barriers keeping water out. These are certainly important, but they are only part of the story. What is often overlooked is the hidden side of flood protection, and that is where pumps come in.
The presence of pumps in a flood defence scheme can make the difference between success and failure. They do not just remove water, they help the entire system work as intended. It is the same principle we set out in why flood barriers still need water pumps.
Why flood walls alone are not enough
A flood wall may look impressive, but no wall is completely watertight. When floodwater builds up on one side, it creates pressure in the ground, known as a hydraulic gradient. That pressure pushes water underneath the wall, where it can rise on the dry side as groundwater.
If that groundwater is not managed, it will eventually equalise with the floodwater outside, meaning your protected area could still flood, filling up from below, or from rainwater that the surface water network cannot drain away while it is falling inside the defence.
The rate of seepage depends on soil type. Sandy soils allow water to pass through faster than clay, but both can allow significant water movement over time.
How pumps manage seepage
To counter this, pumps are used to collect and remove the seepage water from the dry side of the wall, typically through sumps or collection chambers. These sumps capture groundwater, and the pumps transfer it safely back to the wet side, maintaining a lower water level behind the defences. For the detail on how those chambers are built, see our guide to what a sump pump is and how to install one.
Pump capacity is usually based on experience, previous site data, or basic hydraulic calculations. While soil seepage surveys can provide more precision, practical experience often guides the decision-making process.
Pumps and Property Flood Resilience (PFR)
Even where permanent flood walls are not practical, pumps play a vital role in Property Flood Resilience (PFR) measures, as we explain in sump pumps and property flood resilience.
PFR products are most effective in shorter-duration floods and flash flooding. However, during longer events, water can seep through walls, floors or small openings. Having a pump on hand helps keep that ingress under control.
For smaller, short-term floods, puddle pumps are a great, affordable option. They can remove water quickly and efficiently, often down to as little as 1mm, helping to minimise damage. In deeper or more prolonged flood situations, a sump pump may be more suitable.
Choosing the right pump for the job
There are pumps for every situation, from compact puddle pumps you can store in a cupboard to powerful automatic systems that help protect basements day and night, operating without human intervention. Our guide to the best automatic water pump for a flooded basement and to pumping water away automatically at floor level both go into this in more depth.
There are also a range of very powerful water pumps available, such as the APP HD-15 Submersible Site Pump, which has a flow rate of up to 830 litres per minute.
Pumps are available as manual or automatic. For example, if a property's basement regularly flooded, the owner could install an automatic pump which turns itself on when the water reaches a certain level and then turns itself off once it has reduced the water to a set level.
Flooding like this typically occurs via groundwater flooding, or other ingress routes in river or surface water flooding. Below you will see a photo of a property with a small sump that houses an AMA Drainer 301 Automatic Submersible Water Pump 230v. This handles the day-to-day ingress of water that can be normal in a cellar, alongside a much more powerful APP HD-15 pump that activates should the cellar become inundated and additional capacity be required during a flood event.
Working with temporary flood barriers
Water pumps can also be used in conjunction with temporary or roll-out flood barriers, where pumps offer an inexpensive and effective line of defence against floodwaters. Temporary barriers do not require prior installation like flood doors, can be deployed in a matter of minutes, and freestanding temporary barriers such as the Water-Gate will always allow a small amount of water to seep through underneath, as they do not have a formal foundation.
The value of pumps in any flood defence
For as little as £100, a pump can provide a vital extra layer of protection. It is one of the simplest, most cost-effective ways to strengthen any flood defence scheme, whether for a home, business or larger site.
Pumps not only move water away from vulnerable areas, they also support and enhance other defences already in place. From manual puddle pumps to fully automated systems, there is usually a solution for every property and budget. You can browse the full flood defence range to compare options.
Getting the right advice
While we cannot give site-specific recommendations over the phone, we can help you understand the different options available. Our team has extensive experience with flood defence systems, sump and submersible pumps, and can point you towards the most suitable setup for your needs. For a formal review, our Engineering Review Service is also available.
We have also put together a range of guides, videos and how-to articles to help you make the most of your investment and ensure your pump performs when it is needed most.
Order online or call our UK helpdesk on 0115 987 0358.
