Buyers Guide for Selecting the right Rainwater Tank Pump

Buyers Guide for Selecting the right Rainwater Tank Pump

1st Jun 2019

A rainwater tank pump is needed when you want to use to use your rainwater tank water for your home and garden. The water pump pumps the water out of your rainwater tank providing you with pressurised water flow for your house and garden taps.

General requirements for water tank pumps are either to provide water for their house and/or for garden / irrigation use. When selecting a water tank pump for your home or garden you need to consider these following factors:

  • - Distance the water needs to travel between your tank and home
  • - Water pressure requirements
  • - Noise made by the pump
  • - Energy usage

Distance between your Water Tank and House

Distance is a factor because you will need a more powerful multistage type water pump to move water from your tank to your home if your tank is located further away or pipe size is smaller than recommended or if you have a multi-storey house and you have to move water to the upper floors.

Some pumps pre-label themselves as suitable for small or multi-storey homes, but generally you would need a pump that has a head pressure of 20-50 meters in order to move water upwards, against gravity.

Water Pressure

You need to consider what you are using the rainwater for and what kind of water pressure you need.

Water pressure is measured in litres per minute (LPM). If you are using your tank water for toilets and washing machines then a low flow rate could be acceptable if you don’t mind it taking a few more minutes to fill the toilet cistern or washing machine bowl. But if you need the water for showers or even watering the garden, you would want a more powerful pump that can push out water faster – around 20 LPM per tap (which is about the same flow rate of a mains water tap).

When selecting a water tank pump for your suitable LPM, you need to consider the total pressure you require when you have multiple taps operating at the same time. So if you need a tap going in the laundry, and the kitchen and the toilet all at the same time, then you add up the desired water pressure for all those locations to determine the total flow rate required. Match this number to the pump’s “Max LPM” specification.

Water Pump Noise

The amount of noise a pump makes is dependent on its type and how active it is.

To reduce the noise of a free-standing tank pump you can purchase or build a pump cover to enclose it. A cover serves to protect the pump from the elements as well as muffle the noise. However, ensure the cover is large enough to allow airflow so the pump does not overheat.

Submersible tank pumps are installed inside your water tank and sit under the water. This has the effect of muting the pump noises, as well as saving space.

Energy Usage

While it’s tempting to choose the biggest and most powerful pump you can, it’s important to remember that pumps draw energy every time a tap is turned on. The more powerful the pump, the more energy drawn. So buying a pump that is too large for your needs can result in higher electricity bills, offsetting your water bill savings.

To reduce energy usage, aim to reduce the amount of times your pump needs to activate. This can be done by setting up a gravity feed system, a header tank system or by using a pressure tank.

Companies like Grundfos, Davey and Onga are now starting to introduce variable speed household pumps, which are very energy efficient as they automatically run at the required speed needed to match the flow rate required. So they are not running flat out all the time, which saves you money.


Just Water Pumps recommends quality made water tank pumps from well known manufacturers like Davey, Onga, Grundfos, Bianco, DAB. – These brands are well established and have service agents Australia Wide. Cheaper no name brand pumps offer little or no warranty with poor after sales service. You will also find that these cheaper brands will advertise misleading flow and pressure rates with there models. (for more details comparing cheaper pump brands to quality brands - read our featured blog on this topic ) If you need help choosing the right tank pump for your home water tank, please don’t hesitate to contact us for help.