Knowledge centre
Why 2 mm of residual water matters
2026-03-04
A standard submersible pump quickly leaves a centimetre of water behind. What that means on a flat roof, in a cellar or on site.
The last film of water is the hardest
A classic submersible pump draws from the bottom of its housing and needs a water column to keep pumping. Once the level drops below the inlet it pulls air, loses prime and leaves one to two centimetres standing.
On a hundred square metres of flat roof, one centimetre is a thousand litres. That is the difference between a dry roof and half a day with a squeegee.
What the SIMER does differently
The SIMER 6 primes from a 5 mm water level and keeps pumping down to roughly 2 mm, thanks to the patented SIMER system with anti-airlock valve: the air the pump inevitably draws at low levels escapes instead of breaking the water column.
The result is not a technical detail. What is left is a damp floor that dries by itself, not a puddle you have to clear by hand.
Heat matters too
At those levels a pump often runs half dry — exactly when motors overheat. The SIMER has a water-cooled pump housing with a top outlet, plus built-in thermal protection as a final safety net.
It can therefore run far longer un-submerged before cutting out, precisely in the phase where you need it most.
SIMER is a brand of Contimac GMT International — contimac.beEnabling craftsmanship since 1988