What is a Rain to Mains Water Pump System?

A rain to mains water pump system or switch helps you make the most effective use of your tank water or rainwater tank. It allows you to use your tank water or rainwater tank supply first and then switch to mains water supply if your tank water is low or empty.

This set up ensures you maintain a reliable water supply to your toilets, laundry and other areas with no break in supply during the automatic switch over. You can reduce your mains water usage by as much as 40% when a switch is connected to your plumbed-in rainwater tank.

Continual use of your rainwater supplies means:

  • more space in your tank to harvest rainwater when it next rains
  • less mains water usage, reducing your water bill.

RM4000-5 rain to mains pressure pump system - Water Pumps Now 

How do Rain to Mains Water Switches work?

A rain to mains water pump switching device goes by many names including changeover valve diversion valve but they all practically work the same way. Here are some of the names they go under:

  • rainwater harvesting controller
  • mains to rainwater changeover valve
  • rain to mains changeover valve
  • town/tank switch
  • tank to mains interconnection device
  • auto or manual interchange device
  • main switch-over device
  • mains water backup system
  • diversion valve

RM5000-3 submersible rain to mains pump system - Water Pumps Now

The switching device sits between your house pump, your mains supply and your house inlet. It then either automatically detects the tank level of your rainwater tank and switches to mains water if the rainwater tank is low or empty; or you can manually switch between the two water sources.

A backflow prevention device (also known as a dual check valve) must also be installed so that water from your rainwater tank cannot enter (and contaminate) the mains water supply. Backflow prevention devices are available in three hazard ratings: high, medium and low.

Reefe RM7000-3 rain to mains system - Water Pumps Now 

Reefe RM1500-2 rain to mains change over valve

Should I pick an automatic or manual Rain to Mains System?

A rain to mains water switch can be either automatic or manual:

  • An automatic switching device detects when rainwater tank is low then switches to mains water. It typically uses either a float switch in the rainwater tank, or detects the rainwater tank water levels based on pump pressure. Because it is automated, it provides you with a continuous water supply but it costs more than a manual switch and requires electricity to run.
  • A manual switching device requires you to go outside to your rainwater tank and manually open/close the tank and the mains valve. While manual switches tend to be reliable, cheaper and don’t use electricity, you need to leave the comfort of your home each time you want to adjust your water source.

While a manual device would suit most homes, some states actually require that an automatic rain to mains switching device is installed – such as South Australia and some areas of Queensland. Make sure you check your local council requirements if you are unsure.

If you are looking for an automatic rain to mains switch, we recommend the Reefe Rain to Mains Pump System which automatically manages the switch over. There are set ups for supplying part of your house or your entire house depending on your tank size.

Paul Girdler

Paul Girdler, Managing Director/ Sales
Water Pumps Now Your Online Pump Shop

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