Booster Pump Size Guide: What Size Booster Pump Do I Need?
A booster pump fixes weak water pressure from a JoJo tank, borehole tank or low municipal supply. The right size gives strong showers on every floor without burning electricity or wearing the pump out. This guide shows what size you need, which type of control to choose and what else to install. WhatsApp us on 061 744 1001 and we will size it for you.
Quick booster pump size chart
| Home | Pump size | Suggested pumps |
|---|---|---|
| Flat, cottage or 1 bathroom | 0.37 kW | QB60 combo with flow controller, CPM130 combo, RUC 370 VSD |
| 2 – 3 bathrooms, single storey | 0.55 – 0.75 kW | QB80 combo, CPM158 combo, RUC 750 VSD, SSP-100 permanent magnet |
| 4 or more bathrooms, or double storey | 1.1 kW | CPM170 combo, RUC 1100 VSD, BWD 1.1 kW VSD |
| Large homes, guest houses, small farms and irrigation | 1.5 – 2.2 kW | CPM190 combo, CPM200 combo, HMS 1.5 kW Intelli, BWD 2.2 kW VSD |
The chart assumes the pump is fed from a tank at or above pump level and the house is within about 30 m of the pump. Long pipe runs or tanks below the pump need extra sizing.
Step 1: Count the taps that run at the same time
Size the pump for the busiest moment, not the number of taps in the house. A shower uses about 8 – 12 litres per minute and a basin or kitchen tap 6 – 8. If two showers and the kitchen tap run together you need around 30 litres per minute (1.8 m³/h). Add garden taps or irrigation if they run at the same time as the house.
Step 2: Choose the pressure
Most homes are comfortable at 2.5 – 3.5 bar at the taps. For a double storey home, add about 0.3 bar for every 3 m the highest shower is above the pump. Too much pressure (over 4 bar) can damage geysers, mixers and toilet valves, so a geyser pressure control valve should stay in place.
Step 3: Choose how the pump is controlled
- Pressure switch and pressure tank: the most affordable and reliable setup. The tank stores pressure so the pump does not start for every glass of water. See pressure tanks.
- Flow controller (presscontrol): starts the pump when a tap opens and stops it when flow stops. Compact and needs no large tank. Most of our booster pump combos come with a flow controller fitted.
- VSD (variable speed): the pump speeds up and slows down to keep the pressure constant, whether one tap or four are open. It gives the best showers, soft starts and lower electricity use, and runs best on inverters. See VSD pumps.
Step 4: Check where the water comes from
Standard centrifugal and peripheral booster pumps need water flowing into them, from a tank level with or above the pump. If the water is below the pump, such as a well, sump or underground tank, use a self-priming jet pump like the JSWM75 or the stainless steel GJSm800, which can lift water up to about 8 m.
Step 5: Install it properly
Fit a non-return valve and a ball valve on the suction side, a pressure gauge on the outlet and a pressure tank where needed. Keep the suction pipe short, at least the same size as the pump inlet, and protect the pump from rain and sun. If the tank can run empty, add dry-run protection. Fittings and spares are in booster system components.
Booster pumps and load shedding
On an inverter, a VSD or permanent magnet booster pump is the best choice because it starts softly and draws far less power than a standard pump. For off-grid homes, the SQB250 solar booster pump combo runs directly on 24 V DC solar power.
Frequently asked questions
What size booster pump do I need for a 3 bedroom house?
A typical 3 bedroom house with 2 bathrooms needs a 0.55 to 0.75 kW booster pump giving about 3 bar. If the house is double storey or more than two showers run at the same time, choose 1.1 kW.
Pressure switch, flow controller or VSD: which is best?
A pressure switch with a pressure tank is the most affordable and reliable. A flow controller is compact and needs no large tank but the pressure varies more. A VSD gives constant pressure at every tap, soft starts and lower electricity use, making it the best choice for comfort and for inverters.
Can I use a booster pump during load shedding?
Yes, if it is connected to an inverter or backup power. VSD and permanent magnet booster pumps use the least power and start softly, so they work best on inverters and solar.
Why does my booster pump switch on and off all the time?
The most common cause is a flat or burst pressure tank bladder. Other causes are a leaking non-return valve, a dripping tap or toilet, or a leak in the plumbing. Check the tank pre-charge first.
Can a booster pump suck water out of a well?
A normal centrifugal booster pump needs water to flow into it, for example from a tank above or level with the pump. To lift water from a well or a tank below the pump, use a self-priming jet pump, which can lift up to about 8 m.
Do I need a non-return valve with a booster pump?
Yes. A non-return (check) valve on the suction side keeps the pump primed and stops water draining back, which protects the pump and keeps the pressure stable.
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Browse all booster pumps, booster pump combos, VSD pumps and pressure tanks, with delivery across South Africa. Need help? Call 012 881 1962 or WhatsApp 061 744 1001.