Dewater and pump floods

Dewatering means getting water out of where it has collected and shouldn't be: a trench, an excavation, a basement, a cistern or a flooded area. On site it's done with an engine-driven pump (dewatering pump) that sucks the water up and sends it away through a discharge hose.

They're the diameter of the suction and discharge ports: 3″ on the SQWP30 PRO and 4″ on the SQWP40 PRO. More inches means more water per hour: 30 m³/h for the 3″ and 40 m³/h for the 4″, per their spec sheets. The hose matches the port diameter; reducing it cuts flow.

Work out the water volume (length × width × depth) and divide it by the flow. A basement of 8 × 10 m with 50 cm of water is 40 m³: at least 1 h 20 min with the 3″ (30 m³/h) and at least 1 hour with the 4″ (40 m³/h). «At least», because real flow drops the higher the water has to go and the longer the hose.

Fill the casing with water (priming), connect the suction with the strainer on and start it. Send the discharge far from where you're pumping so the water won't flow back. Never start it dry.

A trench or basement with medium flow → the 3″ SQWP30 PRO (30 m³/h, 13 m total head). A large flooded area or water that has to go higher → the 4″ SQWP40 PRO (40 m³/h, 16 m). The calculator on this page tells you which one for your flow and head.

The 3″ up to 30 m³/h and the 4″ up to 40 m³/h: that's their maximum. The higher the water has to go and the longer the hose, the less real flow you get.

Most often: it wasn't primed, the suction hose is leaking air, or the pump sits more than 8 m above the water. Check the couplings, move the pump closer to the water and prime it again.

It handles water with mud and suspended solids, typical of jobsites and floods. Always use the strainer: one big stone can break the impeller.