Borehole Pump Size Guide: How to Choose the Right Borehole Pump

The right borehole pump gives you enough water without running your borehole dry or burning out the motor. This guide explains the information you need, how to work out flow and head, and which pump size to choose. Send us your borehole details on WhatsApp 061 744 1001 and we will size the pump, motor, cable and controller for you.

What you need to know before you buy

• Borehole diameter: the inside diameter of the casing in mm.
• Tested yield: how many litres per hour the borehole can deliver, from the yield (pump) test.
• Water levels and depth: the static and dynamic (pumping) water level and the total borehole depth.
• Pump installation depth: how deep the pump will hang.
• Delivery: height of the tank above the borehole and the pipe length to it.
• Water need: how many litres a day you use (house, garden, livestock, irrigation).
• Power supply: 220 V single-phase, 380 V three-phase, generator or solar.

Quick borehole pump size chart

This chart is a starting point only. The flow must suit your borehole yield and the pump must deliver that flow at your total head (step 3).

Step 1: Match the pump to the borehole diameter

The pump must slide easily down the casing with room for the cable and pipe. As a guide, a 3″ pump suits casings from about 80 mm, a 4″ pump needs at least 100 mm, a 6″ pump at least 150 mm, an 8″ pump 200 mm and a 10″ pump 250 mm inside diameter. If your hole is bent or partly collapsed, choose a smaller pump.

Step 2: Choose the flow (never more than the yield)

Work out how much water you need per day and how many hours the pump can run. A household uses roughly 200 litres per person per day, plus garden and livestock. Then check the borehole yield: choose a pump that delivers no more than about 70 – 80% of the tested yield. A pump bigger than the yield drops the water level to the pump and burns it out.

Step 3: Work out the total head

Total head is how high the pump must push the water, in metres:

• Pump installation depth (or the dynamic water level, if you know it)
• + height from the borehole top to the top of the tank
• + pipe friction, roughly 1 m for every 10 m of correctly sized pipe
• + pressure needed at the outlet, if you pump straight into the house (1 bar = 10 m)

Example: pump installed at 60 m, tank stand 5 m high and 50 m of pipe to the tank. 60 + 5 + 5 = 70 m total head. You need a pump that delivers your required flow at 70 m, which is far below its “max head” figure.

Step 4: Read the pump curve, not the max head

Every borehole pump has a curve showing flow against head. The max head on the label is the height at almost zero flow. Choose a pump where your total head falls in the middle of the curve so it delivers the flow you need efficiently. If you are unsure, send us the details and we will read the curve for you.

Step 5: Motor, cable and power supply

Single-phase 220 V motors are common up to about 2.2 kW; larger pumps normally use three-phase 380 V borehole motors. The drop cable must be thick enough for the motor current and the cable length, or the motor will overheat. Use our cable sizing chart to check.

Step 6: Protect the pump

Most borehole pumps fail from dry running, overload or bad voltage. A borehole controller with dry-run protection switches the pump off when the water runs low and protects the motor. A variable speed drive adds soft starting and can match the pump to a low-yield borehole.

Solar borehole pumps

A solar borehole pump runs directly from solar panels during the day with no batteries, and fills a storage tank for use at night. It is ideal for farms and areas with load shedding or no grid power. Hybrid models switch to Eskom or a generator when needed.

Frequently asked questions

What size borehole pump do I need for a house?

Most homes need about 1 to 2 cubic metres per hour. With the pump installed at 40 to 80 m, that is usually a 4″ borehole pump of 0.75 kW to 1.5 kW. The exact size depends on your pump depth, the height to your tank and the borehole yield.

Can my borehole pump be bigger than the borehole yield?

No. If the pump draws more water than the borehole delivers, the water level drops to the pump, it runs dry and burns out. Choose a pump that delivers no more than about 70 to 80% of the tested yield, and fit a controller with dry-run protection.

What does “max head” mean on a borehole pump?

Max head is the height the pump can lift water when the flow is almost zero. At your real working height the pump delivers much less water, so always choose from the pump curve at your total head, not from the max head figure.

Single-phase or three-phase borehole pump?

Single-phase (220 V) pumps are common up to about 2.2 kW. Bigger pumps, deep boreholes and long cable runs normally use three-phase (380 V) motors, which start easier and run cooler.

How deep should I install my borehole pump?

Install the pump at least 5 to 10 m below the lowest water level during pumping (the dynamic water level) and a few metres above the bottom of the hole so it does not suck up sand. Your borehole yield test report gives these levels.

Can I run a borehole pump on solar?

Yes. A solar borehole pump runs directly from solar panels during the day and fills a storage tank, with no batteries needed. Hybrid models can also run from Eskom or a generator on cloudy days.

Shop borehole pumps

Browse all borehole pumps, solar borehole pumps, controllers and DIY borehole kits, with delivery across South Africa. Need help? Call 012 881 1962 or WhatsApp 061 744 1001.