Basement flooded: what now and which submersible pump do you need?

Step-by-step plan for a flooded basement

1. Turn off the power. If the water reaches sockets, appliances, or the fuse box, switch off the circuit breaker. If you are unsure, call an electrician first.
2. Find the cause. Rainwater through a light shaft, rising groundwater, a leaking pipe, or backflow from the sewer each require a different solution.
3. Pump out the water. Place the pump at the lowest point, run the hose outside or to a drain that doesn't flow back, and start the pump.
4. Dry the floor. A regular pump leaves a few centimeters of water. A flat suction pump can remove water down to about 2 mm.
5. Ventilate and dry. Open windows or use a construction dryer to prevent mold, and report damages to your insurer with photos.

Which pump for your basement?

How fast will the basement be empty?

Calculate the volume: area × water height. A 20 m² basement with 10 cm of water contains 2 m³, or 2,000 liters. A pump that moves 4,000 liters per hour at your head height will take half an hour to do this. Note: the flow rate on the box applies at 0 meters head height. If the water has to go up 3 meters outside, the pump will pump less. This is how you calculate the head height.

Preventing it from happening again

• Pump pit with automatic pump: create a pit of approximately 40 × 40 cm at the lowest point and place a pump with a float in it. Water flows to the pit and is immediately pumped away.
• Check valve in the pressure line: prevents water from flowing back from the hose and the pump from constantly switching on.
• High water alarm: an alarm warns if the pump fails or the water level gets too high.
• Test twice a year: lift the float and check if the pump starts. See also adjusting and testing float switches.

Water from the sewer? Then a pump only helps temporarily. Have a backflow preventer installed in the drain, or a lifting station if your drain is below sewer level.

Recommended basement pumps

PERMANENT PUMP PIT

HOMA Bully C 140 WA

All-round basement pump with float and cooling jacket, 10 m cable.

€366.95

View pump

NARROW PIT

HOMA C250 WE

Float is inside the pump, plus check valve. Fits in tight shafts.

€421.95

View pump

DRY FLOOR

Simer 6 + CRAB float

Flat suction pump down to 2 mm with sensor, for the last millimeters.

€339.80

View pump set

In case of severe flooding, a complete emergency kit is useful: pump, hose, and couplings in one.

Frequently asked questions

What should I do first if my basement is flooded?

Switch off the power in the basement if the water reaches power outlets or appliances. Only then pump out the water.

Which pump do I need to pump out a basement?

For a flooded basement with clean to lightly polluted water, a drainage pump is sufficient. If the basement gets wet more often, choose a pump with a float in a pump pit.

How do I remove the last few centimeters of water?

With a flat-suction submersible pump. It pumps down to about 2 mm, while a regular pump leaves a few centimeters.

How do I prevent my basement from flooding again?

With a pump pit and an automatic pump with a float at the lowest point, a check valve, and possibly a high water alarm.