Water transfer issues in rainwater harvesting system pumps

Explore the main issues rainwater harvesting system pumps encounter when transferring water from collection to usage point, and learn about our range of solutions.

In this module, we’ll explore some of the most common water issues in rainwater harvesting systems, focusing on problems related to the system pump and transferring water from the collection point to the usage point.

We’ll begin with insufficient water pressure. When rainwater harvesting systems can’t effectively carry water from collection point to point of use, poor water pressure in the installed pump is usually the cause. Residents can often experience slow filling toilet cisterns and washing machines, as well as dry patches in their gardens as water spray distances are usually reduced.

These water issues can result in residents:
* Waiting longer to fill washing machines or toilets
* Replace existing boosters with new systems or invest in bigger upgrades when replacing pump and pipes
* Replanting lawns and plants.

The most common root causes for insufficient water pressure, from the collection point to usage point, can be:
* Not enough pressure to move the water
* Long distance between tank and the usage point
* Incorrect pipe dimensioning
* Poor pump control
* Undersized pump

To ensure your customers have access to perfect water pressure in rainwater harvesting systems, the following Grundfos solutions can solve the issues.
The SCALA2 is recommended in situations where multiple outlets are in use at the same time. It provides constant pressure and will save energy.
The SCALA1 & SCALA1 System are recommended if your customer typically uses one or two outlets at a time and have the need for external input to the pump control. Applications like irrigation can benefit from these solutions.
SB & SBA pumps are submersible solutions. They are recommended if your customer uses only one or two outlet at the time and wishes to save space inside their house.

If you want to learn more about these solutions and which ones fit your system needs, go to your local Grundfos website to see more.

Let’s move on and explore the next issue: no water in connected outlets.
During dry spells, rainwater tanks don’t get replenished, and when the supply runs out, residents can find themselves without water.

In such cases, households often have to manually switch to the mains water supply which can be difficult and time consuming.
In other situations, if residents can’t switch to the mains water supply, they usually have to pay to fill their tank using a secondary water source. Residents also often find they are unable to check the water level in their rainwater tanks, and when rainwater supplies run out, some pumps can run dry and break down as they lack protection features. This can result in residents paying for a replacement pump, which can be expensive.

The most common root causes for issues related to empty rainwater collection tanks can be:
* Long periods of drought
* No automatic method for switching from tank supply to mains water

To ensure your customers can overcome these issues, the following solutions are recommended:

A complete boosting system designed specifically for the management of rainwater. It supports both automatic and manual changeover between the rainwater tank and integrated mains water tank. A float switch detects low water level, and the system automatically switches over to the break tank, which is automatically refilled by a valve connected to water mains.

Other solutions could be:
* SCALA2/SCALA1 - a dry installed self-priming pump solution that requires a separate refill system to be installed.  
* SB/SBA - submersible water pumps that also requires a separate refill system to be installed"
All Grundfos pump solutions have built-in dry-running protection, but please ensure you check availability in your country before starting your project.

Course overview

Modules: 4
Completion time
Completion time: 20 minutes
Difficulty level
Difficulty level: Intermediate