Nearly every pump in domestic and agricultural use is a centrifugal pump: a spinning impeller flings water outwards, and the pump body converts that velocity into pressure. The differences between pump types come from what has been built around that impeller, and those differences decide what each pump is good for.
Surface pumps
Surface pumps sit out of the water and draw it in. They are easy to reach for maintenance, easy to wire, and cheaper for a given output — but they are limited by suction. Roughly 7 to 8 metres of vertical lift is the practical ceiling for any of them, and they must be primed before they will work.
Jet pumps
A jet pump recirculates part of its own output through a venturi nozzle at the inlet. That jet of fast-moving water creates the suction that pulls new water in. The result is a self-priming pump that reliably handles suction lift — the reason jet pumps dominate rainwater tank and shallow well duty.
Good at: drawing from tanks and shallow wells, moderate flow at good pressure, tolerating the occasional air bubble. Not good at: very high flow, or lifting water from below about 8 m.
In the Rural Max range: RM-JP100 (750 W, 55 L/min, 43 m head, cast iron body with brass impeller) and RM-JP200 (2 HP, 130 L/min, 50 m head, for larger houses and longer runs).
The RM-SJP800 is the same idea in stainless steel — impeller, motor shaft and housing — at 800 W, 55 L/min and 48 m head. The extra corrosion resistance matters where the pump lives outdoors or the water is mildly aggressive.
Multistage pumps
Instead of one impeller, a multistage pump uses several in series. Each stage takes the outlet of the one before and adds more pressure. Because the pressure is built gradually, multistage pumps run smoothly, quietly and efficiently, and they hold pressure well as demand changes.
Good at: steady pressure across several outlets at once, high head without a large motor, quiet running. Not good at: dirty water — the tight clearances between stages block easily.
In the range: RM-DJSM1025, a 2 HP five-stage pump producing 90 L/min and 50 m head in a stainless steel body. It is the pick for a house where several taps run simultaneously and pressure needs to stay constant.
Centrifugal transfer pumps
A single impeller in a spiral (volute) casing, with no jet assembly and no staging. This is the simplest possible design, and simplicity buys volume: a centrifugal transfer pump moves far more water than a jet pump of similar power, but cannot push it nearly as high.
Good at: moving large volumes over short vertical distances — dam to tank, flood irrigation, filling troughs. Not good at: pressurising a house; head is limited.
In the range:
| Model | Power | Max flow | Max head | Suction | Fittings |
|---|---|---|---|---|---|
| RM-TF1 | 1 HP | 267 L/min | 18 m | 7 m | 1.5” x 1.5” |
| RM-CP-3 | 3 HP | 500 L/min | 26 m | 7 m | 2” x 2” |
| RM-CP-4 | 2.6 HP | 200 L/min | 45 m | 7 m | 2” x 2” |
Compare the RM-TF1’s 267 L/min at 18 m with the RM-JP100’s 55 L/min at 43 m and the trade-off is obvious — nearly five times the flow, less than half the head.
The two larger models show that “centrifugal” is not one thing. The RM-CP-3 is built for volume: 500 L/min, but only 26 m of head. The RM-CP-4 trades that volume away for pressure — 200 L/min at 45 m, which is jet-pump territory at more than three times the flow. Choose the CP-3 for flood irrigation and rapid tank filling, and the CP-4 where water has to travel uphill or feed a pressurised irrigation system.
Submersible pumps
Submersible pumps sit in the water and push rather than pull. That removes the suction limit entirely, which is why they are the only option for bores, and it makes them self-priming by definition. The water around them also cools the motor.
The trade-off is access: servicing means pulling the pump out.
Drainage and utility pumps
A sealed motor driving an impeller, in a compact body with a strainer at the base. Designed for clean or lightly contaminated water.
Good at: emptying pits, sumps and flooded areas; transferring from a dam; general utility pumping. Not good at: solids, sewage, or continuous high-pressure duty.
In the range:
| Model | Power | Rated flow | Rated head | Max flow | Max head |
|---|---|---|---|---|---|
| RM-QDX370 | 0.5 HP (0.37 kW) | 25 L/min | 16 m | 97 L/min | 17.5 m |
| RM-QDX1100 | 1.5 HP (1.1 kW) | 250 L/min | 15 m | 467 L/min | 17 m |
Both are rated for water in the pH 6–8.5 range at temperatures below 40 °C. Note the gap between rated and maximum figures — the rated point is where the pump is designed to work, the maximum is the edge of its curve.
Macerator and sewage pumps
Where water carries solids, a standard impeller jams. Two designs solve it differently. A macerator pump has a cutting mechanism that shreds solids before they reach the impeller. A sewage pump uses a wide-passage impeller that lets solids through intact.
Good at: slurry, effluent, washdown water, construction dewatering, septic transfer. Not good at: anything requiring high pressure; they are volume-and-tolerance machines.
In the range:
| Model | Type | Rated flow | Rated head | Max flow | Max head |
|---|---|---|---|---|---|
| RM-WQD7 | 2 HP macerator | 117 L/min | 16 m | 350 L/min | 19 m |
| RM-WQD15 | 2 HP sewage | 250 L/min | 15 m | 333 L/min | 19 m |
Choose the macerator where solids are fibrous and need cutting; choose the sewage pump where the priority is volume and the solids can simply pass through.
Bore pumps
A bore pump is a long, narrow, multistage submersible built to fit inside a bore casing. Stacking many small impellers produces very high head from a slim body — the only practical way to lift water from tens or hundreds of metres down.
Good at: deep water, high head, continuous duty. Not good at: dirty water or running dry, which destroys them quickly. Bore pumps must stay submerged.
In the range: RM-BORE2, a 2 HP 4” submersible producing 132 m of head and 67 L/min (4 m³/h) at 2900 rpm, with stainless steel impellers and diffusers, an IP68 rating, a control box and 40 m of SAA-certified cable.
Bore pumps have their own sizing method — see Sizing a Bore Pump.
Side by side
| Type | Typical flow | Typical head | Suction lift | Handles solids | Best use |
|---|---|---|---|---|---|
| Jet | Low–moderate | High | Up to ~8 m | No | Tanks, shallow wells, house pressure |
| Multistage | Moderate | High | Up to ~8 m | No | Constant pressure, multiple outlets |
| Centrifugal transfer | High | Low | Up to ~7 m | Light silt only | Dam to tank, irrigation |
| Submersible drainage | Moderate–high | Low | N/A | Light | Pits, sumps, flooding |
| Macerator / sewage | High | Low | N/A | Yes | Effluent, slurry, washdown |
| Submersible bore | Low–moderate | Very high | N/A | No | Bores and deep wells |
Materials matter as much as type
Two pumps of identical design can have very different service lives.
- Cast iron body — heavy, absorbs vibration, excellent value. Standard on the RM-JP100 and RM-JP200.
- Stainless steel body — corrosion resistant, lighter, better outdoors and in aggressive water. Used on the RM-SJP800 and RM-DJSM1025.
- Brass impeller — hard-wearing and corrosion resistant, a step up from plastic.
- Stainless steel impeller — the most durable option, standard on the bore and stainless models.
- Ceramic mechanical seal — resists wear and leakage far better than a basic seal. Fitted to the RM-TF1.
- Thermal overload protection — cuts the motor before heat damages the windings. Fitted across the domestic pump range.
Once you have picked a family, How to Choose the Right Water Pump will get you to the model.
