How to select the right pump for boosting water from a roof tank

Learn about boosting water from a roof tank and what to consider to select the right pump for the job.

When a water storage tank is placed on the roof of a house, the requirements for the booster pump used differ slightly from the requirements for pumps used to boost water from a storage tank on or below the ground.

In some cases, gravity can create a sufficient pressure to distribute water from a roof tank with no pump installed. However, if water pressure becomes too low in the taps, a booster pump may be necessary to increase water pressure. When a booster pump is installed on the roof in connection with a storage tank, water coming from the tank into the home could have a high pressure. In order not to burst pipes or installations, such as toilets in the home, pumps used for boosting from roof tanks must be selected according to the maximum pressure or alternatively use one where you can adjust the pressure.

The placement of the pump is crucial to the requirements for it. If the pump is placed on the roof with the tank, it must be able to withstand the harsh conditions from large temperature ranges, wind, rain and dust. This can be alleviated by placing the pump underneath the roof of the house; however, this brings the pump closer to the residents, creating a need for a pump with a lower noise-level. Just as it is the case for water storage tanks on or below the ground, roof tanks can contain air bubbles, debris and dirt meaning that the booster pump must have good air-handling capabilities and preferably be fitted with a separate inlet filter for protection.

Similarly, a roof tank can run dry if water is used faster than the tank is filled, and therefore we recommend selecting a pump with dry-run protection. For boosting from a roof tank, we recommend selecting the Grundfos UPA, SCALA1 or SCALA2. The UPA is ideal for indoor installation, as it is compact in size and is installed in-line directly on the pipe with a low noise-level. However, it cannot withstand the conditions of an outdoor installation, for which we instead recommend using the more robust SCALA1 or SCALA2. If using the SCALA1, make sure to select a variant with the correct output pressure. The SCALA2 will give you the more advanced feature of the so-called “perfect water pressure” which allows you select the pressure that fits the application perfectly, and the pump will automatically adjust the output pressure to the selected level.

As the SCALA2 is also relatively compact in size and has a low noise-level, it can be installed both indoors and outdoors and offers the most advanced features for boosting from a roof tank. The SCALA1 and SCALA2 both offer leakage alarms that will send the pump into an alarm mode if a leaking pipe is detected. This will prevent damage to the pump as well as unnecessary starts and stops. Both the SCALA1 and the SCALA2 also have a maximum runtime that will prevent the pump from continuing to run uncontrolled in case a leaking pipe is interpreted as demand in the system. The SCALA2 has a maximum runtime of 30 minutes, while the maximum runtime of the SCALA1 is adjustable through the Grundfos GO app. 

Course overview

Modules: 6
Completion time
Completion time: 25 minutes
Difficulty level
Difficulty level: Basic