It’s a question we get asked a lot!
When a basement is constructed, a waterproofing cavity drainage system (like a Delta Membranes system) is installed, and a part of that system is a pump station (sump) and sump pump.
Groundwater
When basements are built, the first line of defence should be the structure, but sometimes, water may get through the structural joints. The Type C cavity drainage system stops that water from coming through to your walls and diverts it to a sump within the basement. When the water enters the sump, the sump pump/s discharge the water away to the main sewer. Depending on the construction, sometimes there is a lot of water and sometimes the is no water. The amount of water entering the basement can also change over time, as more basements are built changing the route of underwater streams and also as the water table rises.
Foul water (wastewater)
If a basement has facilities in it, like toilets, basins, etc. then a foul water pump station would be installed at the time of construction. As the basement is below the main sewer level, then water is flushed in the basement it can’t defy gravity and go up! This is where the pump station comes in… the water from the facilities flows under gravity to the sump, where it is then pumped away to the main sewer. If there is a swimming pool in the basement, during backwashing this water will also usually be discharged via the pump station.
Did you know, almost all basements in London have a pump station. If you have a basement (or even if you don’t) and you’re reading this, we’d love you to vote in our poll below…