Pumps

A surface-mounted pump is installed externally, while a submersible pump is installed within the tank. The right option depends on the tank configuration, site conditions and performance required from the system.

No. Maximum flow rate alone does not show how a pump will perform under the conditions of the installation. The pump flow chart shows the relationship between flow and head and provides a better indication of expected performance.

Start with the outlets the system needs to supply and how many may be used simultaneously. Then check the required flow and pressure against the pump flow chart, taking into account factors such as property height and the distance the water needs to travel.

Consider the number and type of outlets, how many may operate at the same time, the required flow and pressure, whether the property is single or two-storey, the location of the tank, and whether a surface-mounted or submersible pump is required.

As part of commissioning, test the Rain to Mains switching function and confirm the system switches between rainwater and mains supply correctly. Check that mains water supply is available when required.

Check the system for leaks and confirm pump operation, water flow and pressure. Test the Rain to Mains switching function and mains backup, check connected fixtures, and confirm the controller is set and operating correctly. The system should also be checked for excessive cycling, unusual noise or vibration.

Before installation, confirm the pump is suitable for the application and can meet the required flow and pressure. Check which outlets will use rainwater, the location and type of rainwater tank, power supply, pipe sizes and required connections. Always refer to the installation instructions for the specific products being installed.

Rainwater harvesting offers many benefits, including: 

• Savings: Using rainwater as a natural source of water can reduce your utilises bill, offering significant savings over time. 
• Required water source: In some areas, rainwater harvesting can be a crucial source of water drinking and other uses. It is recommended in several jurisdictions around Australia to reduce reliance on main water supplies. 
• Environmental benefits: Rainwater harvesting offers environmental benefits including decreased stormwater runoff and reduced near for main water usage. When you take advantage of rainwater harvesting, you can contribute to more sustainable water usage. 

There are a few factors to consider when choosing a water pump for rainwater harvesting:

• Pump type: With multiple pump types available on the market, you’ll have to decide which is right for your task or purpose. For example, submersible pumps are used to “push” water rather than “pull it”, and are less noisy and more space-efficient. Jet pumps are generally available for a cheaper upfront price and can be used for a more versatile range of functions.
• Required flow rate: Flow rate determines how quickly water is delivered. Required flow depends on how your rainwater tank or other water source is used. Flow rate is usually measured in litres per minute.
• Required head: Head is the vertical distance that water must be moved by a pump to its destination. This is an essential consideration, as different pumps are designed to move water at different vertical distances.
• Required pressure: Purchasing a pump with the right pressure ensures that water reaches its intended outlet with the required force. Pressure for water can be calculated using P(kPa)=9.81xhead(m).

Contact your local plumber to size up correctly for each individual application.