Choosing a booster pump for your tank
Head, pressure, flow and controls: what matters when you pick a pressure pump for a JoJo tank or a weak supply.
A booster pump pushes water from a tank through the house at a steady pressure. Five things decide whether it will feel right in the shower, and whether it is allowed.
Connect it the right way
In South Africa a booster should draw from a tank that the municipal pipe fills, not straight from the municipal main, unless your municipality approves (SANS 10252-1). Rainwater or borehole water must never be connected into the municipal plumbing. Ask a registered plumber.
Pressure and head
Pump datasheets give the head in metres: how high the pump can lift water. Pressure is the same thing in other units: 10 m of head is about 1 bar. Homes are usually comfortable at about 2 to 3 bar, and there is a ceiling too: SANS allows at most 6 bar at the taps, and your geyser's pressure valve (often 400 kPa, i.e. 4 bar) sets the real limit for hot water. The pump has to cover the height from the tank to the highest tap, the pipe losses and the pressure you want at the tap, so a pump whose maximum head only just reaches your target will feel weak.
Flow
Flow (litres per minute) says how much water it can deliver. A water-saving shower head or tap uses roughly 6 to 12 litres a minute; older shower heads and kitchen taps use about 12 to 20. Count the taps that may run at once. A pump's maximum flow and its maximum head are at opposite ends of its curve: it can't give both at the same time.
How it switches on and off
- Pressure switch or flow controller: the pump runs at full speed when a tap opens and stops when it closes. Simple and cheap, but the pressure can surge and drop, and a pressure-switch system needs a small pressure tank or the pump keeps switching on and off.
- Constant pressure (variable speed, "VSD" or inverter-driven): the pump speeds up and slows down to hold the pressure steady. Smoother and usually quieter, and it often uses less power at low flow. Many compact "smart" boosters work this way, but not all: some are fixed-speed with a built-in controller.
A bare pump with neither needs a separate controller; shops often sell "auto" kits that include one.
Protection
Look for dry-run protection: it stops the pump if the tank runs empty, which would otherwise damage it. A pump's IP rating covers water and dust, not sun or frost, so give it a ventilated cover outdoors.
In a power cut
A booster pump needs power. On a backup system it adds to the load your inverter must carry, and a pump motor briefly draws more when it starts, so check that your inverter's surge rating can handle it. Variable-speed pumps usually start more gently.
The pump comparison in this directory lists each model's maximum head, flow, power and how it is controlled, from the makers' own datasheets.
Written by the Halvora Directory team and checked against public sources (7 Nov 2026). General information, not advice for your installation.