Flow is quoted at zero height, and the garden is not at zero height
A garden pump takes water from a butt, a tank or a well and pushes it into a hose, and it is sold on a number that describes none of that honestly. The flow rate — 3 000, 4 500, 5 000 litres per hour on this shelf — is measured with the outlet open at the same height as the pump. Lift the water and the flow falls; lift it far enough and it stops. The figure that says how far is the head, quoted in metres: 43 m, 45 m, 48 m and 50 m on these listings, and a pump rated 5 000 l/h at zero head might deliver a third of that at twenty metres. A page that prints only the first number is describing a laboratory. The suction height is the other half of the same geometry and it has a hard physical limit: no surface pump lifts water more than about eight metres up to itself, whatever it says, and this shelf quotes 7 to 9 m. Below that, the pump has to be primed and the suction line has to be airtight — the commonest failure on this family is not the pump but the joint before it. The motor power runs 600 to 1 300 W and correlates loosely with both other figures. Then the two practical columns: the connections, which are threaded in inches and decide what fits without an adapter, and the material — stainless housings on the jet pumps here, plastic on the cheaper garden ones — which decides what happens after three winters. Several of these are sold as pressure-switched house water units rather than plain pumps, which is a different machine doing a related job. We compare flow rate, head, motor power, suction height, connections, material and weight.
600 W, 3 200 l/h, 7 m suction, 1" female thread, drain plug
A 600 W jet pump at 3 200 l/h with a 7 m suction height, a Noryl impeller and a drain plug for the winter.
Best for: Watering from a butt or emptying a pond, where lift is short and the pump lives indoors in winter
650 W, R1" male 33.3 mm ports, filling opening, drain screw
A 650 W pump with a well-placed filling opening, a drain screw and R1" male connections on 33.3 mm.
Best for: Straightforward garden watering, for a buyer who will find the hydraulic figures elsewhere
600 W, 3 000 l/h, 3.5 bar, stainless shaft, brass threads
An entry pump with a stainless shaft, brass thread connections, 3.5 bar and two G1" nipples supplied.
Best for: A first pump for hose and sprinkler use, where getting it connected matters as much as the figures
1 200 W, 5 000 l/h, 50 m head, 8 m suction, 19 L stainless vessel
A 19-litre stainless vessel with an automatic pressure switch, 5 000 l/h and 50 m of head, on a stainless pump body.
Best for: A permanent rainwater or well supply where the water is drawn in short bursts through the day
1300 W, 5 000 l/h, 50 m head, 7 m suction, stainless, filter
A stainless-bodied 1300 W pump at 5 000 l/h and 50 m of head, with an inlet filter, rubber feet and a tool-free drain plug.
Best for: Drawing from a rain butt or a shallow well where the water carries debris
800 W, 5 200 l/h, 43 m head, 4.3 bar, 8 m suction, 19 L steel tank
A pressure vessel set rather than a plain pump: 19-litre steel tank, pressure gauge, and it starts and stops itself.
Best for: Supplying an outside tap or an irrigation system from a cistern, where the pump should run on demand
600 W, 3 300 l/h, 35 m head, 3.5 bar, 8 m suction, G1"
3 300 l/h, 35 m head, 3.5 bar and an 8 m suction height, with G1" suction and delivery ports.
Best for: A medium garden watered from a butt or a cistern, where the numbers need to be checkable before buying
1 200 W, 5 000 l/h, 45 m / 4.5 bar, 9 m suction, stainless
A stainless jet pump with a 9 m suction height — the highest here — a Noryl hydraulic unit and an anti-vibration handle.
Best for: Drawing from a deep cistern or a well, where the lift is the binding constraint
4 500 l/h, 48 m head, 24 L vessel, stainless housing, 1–3 sprinklers
A 24-litre vessel, a mechanical seal system, an electronic pressure switch, and a non-return valve and thread tape in the box.
Best for: A permanent installation on a cistern or a well, supplying one to three sprinklers
