Choosing, sizing and using water pumps, written in plain English for homeowners, contractors, facilities managers, and anyone who has water where it shouldn't be.
Most pump problems we see come down to one thing: a pump asked to do the wrong job. Oversize it and you waste energy, add wear and shorten its life. Undersize it and it can't keep up, runs hot, and fails early.
This handbook walks you through getting it right (head, flow, friction losses, pump types and controls) so you end up with a pump that's the correct size for the job, not the biggest or most expensive available. A few minutes reading here saves time, money and premature failures. And it's designed to help you have a more useful conversation with us (or anyone) when it's time to buy.
Sections one to five are the practical guide; six to eight are reference.
Who this guide is for, and how to use it.
Replacing, specifying, sizing, and the questions we'll ask.
Axes, duty points and the middle-third rule.
Centrifugal, submersible, surface, engine, diaphragm, specialist.
Floats, probes, pressure switches, VFDs, motor protection.
How to read our spec sheets, plus an IP ratings reference grid.
An A–Z of pump terms in plain English.
Phone, email, web, and what to send us.
If pump curves feel abstract, here's the same idea told three ways. Where a pump sits on its curve is a lot like what gear you're driving in.
Very high head, very low flow. The engine strains against resistance, progress is slow, and everything's under stress.
In pump terms: too much vertical lift, long pipe runs, undersized hose or restrictive fittings.
The engine is relaxed, economy is good, wear is low, and it'll happily run like that for hours.
In pump terms: operating around best efficiency, balanced flow and pressure, sensible energy use, long life.
Very little head, extremely high flow. The engine spins furiously against almost no resistance.
In pump terms: running toward the high-flow end, where efficiency drops and mechanical wear climbs.
A well-sized pump is the cruising-in-the-right-gear pump. That's what the middle-third rule is really about, and why we ask so many questions before recommending a unit.
A typical 25 mm bore hose at 100 l/min loses roughly a metre of head every few metres of length. Step up to 50 mm bore and that loss drops sharply. If you're running more than a few metres of hose, oversizing the bore is usually cheaper than upsizing the pump.
Submersibles sit in the water: self-cooled, no priming, no theoretical suction limit. A surface pump has to draw liquid up against atmospheric pressure, which caps it at roughly 6 metres of suction lift for water. Easier to service, but more limited.
Read the guide, then explore the collections it talks about.
Sit in the water, self-cooled, no priming. Flood removal, cellar drainage, sewage, dewatering and borehole supply.
Shop submersibles 02Sit above the water and draw it up through a suction hose. Easy to service, with the motor kept clear of the liquid.
Shop surface pumps 03Engineered to remove water down to very low residual depths, as little as 1 mm, where a standard submersible leaves water behind.
Shop puddle pumpsWe'd rather spend ten minutes helping you specify the right pump than sell you the wrong one. Once you have the duty (how much water, how high, how far), our team can size a pump in a single phone call. Try the free Water Pump Performance Calculator for friction losses on your hose and pipe run.
The information in this guide is provided for general guidance. Pump performance figures depend on the specific installation. We make every effort to ensure accuracy but cannot accept responsibility for losses arising from errors or from application of this guidance without verification. For critical installations always seek written confirmation of specification from our sales team. · FAWP-HB-01 · Edition 01 · 2026
