How to select the right pump for boosting mains water

How to select the right pump for boosting mains water

Learn about boosting mains water and what to consider to select the right pump for the job.

* Connecting pumps directly to the main water supply is not legal in South Africa

In some areas of the world, low or varying pressure of mains water is a common issue due to changes in demand in the water mains throughout the day. To stabilise the water pressure in a home using mains water, a booster pump can be installed. However, boosting water directly from water mains is not legal in some countries. Instead, a water storage tank must be installed from which water can be boosted into the home or up to a roof tank.

Always make sure to check the local legislation before installing a booster pump directly onto the water main. 

Booster pumps for boosting mains water will often be installed inside the home, creating a need for a low-noise pump that will not disturb the residents. Even if installed outside, a low-noise pump is recommended in order to not disturb neighbours if the pump starts during the night.

Water pressure in water mains can be very high at times. Therefore, you must choose a pump with a sufficient material strength to handle the combined inlet and pump pressure. As water pressure in water mains also varies significantly throughout the day, it is beneficial to select a booster pump that is able to not only add to the pressure, but also to stabilise pressure so that the end user will experience a constant water pressure throughout the day, regardless of fluctuations in the water mains. Let’s look at an example: If pressure in the water main is 2 bar, and the pump can deliver 5 bar, this will create a combined pressure of 7 bar, which may be an issue if the pump is not able to handle a pressure of more than, for instance, 6 bar.

However if it is a constant pressure pump it will only build the pressure according to the desired setpoint. In the example, if the setpoint of the pump is 4 bar the speed of the pump is adjusted to deliver 2 bars so the total pressure becomes 4 bars. Last but not least, pumps used to boost mains water must be approved for drinking water.

For boosting mains water, we recommend selecting the Grundfos JET pump & booster, SCALA1 or SCALA2. The JET pump & booster will cover the basic needs for boosting from water mains with a material robustness up to 6 bar and drinking water approval. However, due to its significant noise level, the JET pump & booster should only be used for outdoors installations under a shed or a lean-to. The SCALA1 offers a lower noise level suitable for indoor installations, while the SCALA2 offers the lowest noise level along with the most advanced option for boosting from water mains with constant pressure.