Flood Pumps

How to choose a flood pump

Start with power. In a flooded building the electrics may be off or unsafe, and an engine pump can sit outside on dry ground with only the suction hose in the water. Where a safe supply is available, an electric submersible is quieter and needs no fuel. On construction sites, choose 110v models to work from a site transformer.

Next, look at what is in the water. A drainage pump such as the Koshin Ponstar PX passes fine solids only (around 3mm), so water with heavier debris needs a vortex or trash pump. Finally, decide how dry you need the floor. A standard drainage pump loses suction once the level drops below its intake, which is where a residue pump takes over.

Flood pumps we stock

The range falls into four groups:

• Petrol engine pumps: the Koshin KTH compact trash pumps run on Honda petrol engines, pass solids up to 30mm and move up to 1600 litres per minute across the range. For cleaner water there are the Koshin SEV, Koshin STH semi-trash, Koshin SEH and Villiers RT pumps.
• Submersible drainage pumps: the JS Heavy Duty Contractor range comes in 110v or 230v, manual or automatic, with cast iron components and twin mechanical seals. Alongside it are the JS RS top outlet and JS RS 100 pumps, the Koshin Ponstar PX and PBX, the Flotec Compac and the stainless steel Jung Drenox.
• Dirty water and vortex pumps: the Vort Buddy (230v with a float switch fitted), the Flotec VIP and VIPVort and the Jung Omnia stainless steel vortex pumps handle water with soft solids.
• Residue pumps: the Koshin Ponstar PXL in 110v and 230v, the JS RSD-400 and the JS RSD 150 Puddle Buddy take water down much lower than a standard drainage pump.

Setting up a flood pump

Match the hose to the outlet: the Ponstar PX has a 2 inch outlet and takes standard 2 inch (50mm) hose. Layflat hose is quick to lay out. Run the discharge far enough away that the water cannot drain straight back towards the building.

Stand a submersible on a firm, flat surface, not in soft mud. Never use mains equipment in flood water unless the supply has been checked as safe and is RCD protected. For standby use, an automatic pump with a float switch starts by itself as the water rises.

Related applications

If water comes back every time it rains, a permanent pump in a pit is the better answer: see basement and cellar pumps. For shallow water on flat floors, browse puddle pumps or read our puddle pump guide. For excavations and trenches, see dewatering pumps.

Frequently asked questions

What is the best pump for a flooded house?

If the power is safe to use, a 230v automatic submersible drainage pump with a 2 inch outlet suits most flooded rooms and cellars. If the electrics are off, use a petrol engine pump positioned outside. Finish with a residue pump to take the floor down to a thin film before drying out.

Can I run a petrol pump inside a building?

No. Petrol engines give off carbon monoxide, so the pump must stand outside in open air with the suction hose run in through a door or window. Keep it well away from openings so the exhaust cannot drift back inside.

Will a flood pump pump a floor completely dry?

A standard drainage pump stops drawing once the water drops below its intake, so it leaves a layer behind. Residue pumps such as the Koshin Ponstar PXL and JS RSD range are built to go much lower. Many crews use both: a drainage pump for the bulk of the water, then a residue pump to finish.

Should I buy a 110v or 230v flood pump?

Buy 230v for homes and most commercial premises, where the pump runs from a normal socket on an RCD-protected circuit. Buy 110v for construction sites and plant hire, where tools run from a site transformer. The JS Heavy Duty Contractor and Koshin Ponstar PX ranges both come in either voltage.

Can a flood pump handle sewage?

Most cannot. Drainage pumps pass fine solids only, and the Vort Buddy is not suitable for toilet waste, wipes or sanitary items. If flood water is contaminated with sewage, use a sewage vortex pump from our sewage pumps range or an engine-driven trash pump such as the Koshin KTH.