How-to: Choose a Sump Pump

What is a sump pump?

Sump - a pit or hollow in which liquid collects

Sump pump - a submersible pump for removing water from low levels of buildings, installed in a sump at the lowest part of the floor. Typically automatic, they can largely be left alone to control water levels by pumping collected water to the nearest drainage point.

They are very effective at controlling water levels but are not designed for pumping raw sewage or aggregates due to the solids particles; for these applications you will need a sewage pump.

Submersible sewage pumps may sometimes be used in a sump application, but never the other way around.

How does it work?

Excess water, such as from a flood or high groundwater, drains into the sump. This lifts a level control component that activates the pump at a predetermined point, turning the pump off once the lower level is reached again. Water is routed to another location like the nearest foul drain.

Selecting the right Sump Pump

Selection requires careful consideration, the most suitable sump pump for your specific application will also be the most efficient and reliable.

The first thing to consider is the volume of water to be handled. This is difficult to measure and will vary according to conditions, so it’s safest to work to your highest estimate. Use this figure to inform your following decisions:

The dimensions of the sump hole will determine the amount of water that collects before the pump activates and needs to be big enough for access to the pump in case of maintenance.
The dimensions of the discharge head will determine how quickly water can be pumped out (maximum flow rate).
The maximum power output of the pump will affect how far water can be pumped.
Solids handling - any solids present in the water you pump will need to be accounted for, if the pump is not designed to allow them through it is likely to experience a blockage and subsequent breakdown.

The pipework for carrying nuisance water away depends on whether your application is temporary or permanent. For a temporary solution a flexible hose can be used, but for longevity in a permanent application galvanised steel or ABS plastic are more robust.