Sump pumps are brilliant when they’re specified and installed properly but can pose challenged if they’re not. We see the same issues repeatedly when our team are commissioned to undertake surveys or post‑installation inspections, and many of them are avoidable with a bit of foresight during design and install.
Here are the five mistakes we see all the time, and how to avoid them.
You wouldn’t believe how often we find pumps installed with the electrical cable set into poured concrete.
It works right up until the day the pump fails, and then the only way to replace it is to break up the ground, where as you want to be able to pull a new cable through conduit.
What to do instead:
All cables should run in conduit, accessible and replaceable without excavation.
A sump pump is pointless if water rushes back down the discharge pipe as soon as the pump stops.
We see this, pumps turning on, only for where they turn off, any water that is held in the pipework to flow back into the chamber, then causing the pump to need to turn on again. A sure-fire way to drive premature failure and increase your electricity usage. Thought should also be given to the discharge location, if there is any chance the outlet could be under water, a Non-Return valve is vital to protect the pump from becoming a route of ingress.
Fix:
Fit an NRV on the discharge pipe or pump outlet, as pictured below and included in the FPS Packaged Pump Stations.
This issue is surprisingly common, and it’s one that can quietly undermine an otherwise good pump installation.
In sump chambers, fixed discharge pipework is typically used inside the chamber rather than flexible hose. However, it’s essential that this pipework is pressure-rated and properly jointed.
The image below was taken during a Flood Risk Assessment site visit undertaken by FPS Environmental Ltd. It shows standard bathroom waste pipework connected to a submersible pump. This type of pipe is designed for gravity drainage, not pressurised flow. It may perform adequately under light use, but when the pump runs at full duty, a joint could fail under pressure.
Notably, a screw has been driven through the pipe to hold a fitting in place. This is a clear sign the installation is relying on improvised restraint rather than proper solvent-welded or compression pressure fittings. In a permanent installation, discharge pipework should be securely jointed and mechanically stable without improvised fixings.
It’s also important to consider where the water is being pumped to. If the discharge runs uphill, over long distances, or is buried externally, flexible layflat hose is not suitable as a permanent connection.
Finally, the hose or pipe must correctly match the pump outlet. Using the right hose diameter, hose tail, and stainless hose clip ensures unrestricted flow and prevents vibration-related loosening over time. Our video below explains this in more detail.
Fix:
Check the outlet size before buying a hose.
If the hose is wrong, the pump can’t do its job.
A float switch needs room to rise and fall. In a tight chamber, it could be caught or become snagged, meaning the pump never activates. You should also consider at what level the water needs to turn off and on, a pendant float switch generally requires greater depths and isn’t accurate.
Fix:
If space is tight, use:
Pumps like to be run, like a car, if you were to leave it unattended and not use it, its more likely to seize. This is important with flood pumps, don’t leave them turned off and never run them. Every pump needs:
In 90% of flooded basements we attend, the pump hadn’t been tested for months (or years).
If the pump needs to be stored, ensure it is stored dry, any water has been removed first, and for best results coat the pump and impeller in GT85 or similar.
Fix:
Test monthly.
Replace pumps before they die, not after.
Most pump failures aren’t pump failures at all, they’re design or installation failures.
If it’s a critical part of your flood resilience setup, treat it like any other critical bit of kit:
accessible, serviceable, protected, and backed‑up.
If it is important to the running of a site, such as a Sewage Pump, keep it serviced regularly, and if its for emergency use such as flood resilience, have at least 1 spare pump, per installed pump.
In property-level protection schemes, barriers may seal doors and openings, but water can still enter through walls, floors, and service routes. Measures like repointing or tanking reduce this, but rarely eliminate it entirely.
The EGO 500 SELS uses electronic water-sensing probes rather than a traditional float switch. This allows low level automatic operation in shallow sumps or tight chambers where floats may otherwise jam, or stick - whilst also not pumping as low...
If it’s a critical part of your flood resilience setup, treat it like any other critical bit of kit:
accessible, serviceable, protected, and backed‑up.
