What is a submersible pump with flat suction?

How does a flat suction pump work?

With a regular submersible pump, the inlet is a few centimeters above the bottom, around the impeller. If the water drops below that inlet, the pump draws air and the water flow stops. With a flat suction pump, the inlet is just below the pump, with a narrow gap between the base and the floor. This allows it to continue drawing water until almost nothing is left.

Many flat suction pumps have a de-aeration valve or jacket cooling. This keeps them cooled even at very low water levels and ensures they continue to move water.

Flat suction pump or regular submersible pump?

What do you use a flat suction pump for?

• Basements and cellars after flooding or a leak;
• Flat roofs and terraces: pumping water from a flat roof;
• Crawl spaces: keeping crawl spaces dry;
• Swimming pools, pond containers, and tennis courts to empty for maintenance or winter;
• Construction and installation: drilling and sawing water, elevator shafts, and stairwells.

Manual or automatic?

Manual: you plug it in and unplug it when the water is gone. Affordable and ideal for installers and one-off jobs. Automatic: an electronic sensor switches the pump on when water is present and off when it's gone. Indispensable if the pump is permanently installed. A regular float switch works poorly with a flat suction pump because it only activates with several centimeters of water. That's why automatic flat suction pumps have a sensor.

Do not let a manual flat suction pump run dry for long. As soon as the water is gone, turn it off. If you won't be present, choose an automatic version.

What to look for when choosing?

• Type of water: only clean water? Then the lightest pump will do. Some sand or dirt? Choose a model that can handle solid particles up to 3 mm, or a robust construction flat suction pump.
• Capacity and head: does the water need to be moved far or high (e.g., from a roof down or out of a basement up)? Check the pump curve.
• Weight: for roof or emergencies, a light pump is handy; on a construction site, a heavy cast iron one.

Recommended flat suction pumps

MOST POPULAR

Pentair Simer 6

Down to 2 mm, 6,000 l/h, with built-in non-return valve.

€269,50

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SLIGHTLY CONTAMINATED WATER

HOMA C240 W Flat

Down to approx. 2 mm, solid particles up to 3 mm, stainless steel motor housing.

€331,95

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CONSTRUCTION AND PROFESSIONAL

SPT FSP 400W

Robust cast iron flat suction pump with vortex impeller, down to 1 mm.

€490,00

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Automatic? Choose the Simer 6S or the Simer 6 + CRAB. Did you have a Simer 5? Read what the Simer 6 does better.

Frequently asked questions

What is a flat suction submersible pump?

A submersible pump that sucks water from the bottom down to a residual level of approximately 1 to 2 mm, so you don't have to mop afterwards.

How many mm does a flat suction pump pump down to?

Most flat suction pumps pump down to 1 to 2 mm of residual water, depending on the model and how flat the surface is.

Can a flat suction pump handle dirty water?

Limitedly. Flat suction pumps have a narrow inlet and are intended for clean to slightly contaminated water. For mud or fibers, choose a dirty water pump.

Does a flat suction pump have a float switch?

Manual models do not. Automatic flat suction pumps use an electronic sensor because a regular float switch only reacts with several centimeters of water.