Guide to Water Pump Selection

Selecting the best water pump solution for your needs is vital to ensure you have the right size pump for the job at hand. You need to understand a few factors when considering water pumps such as:

  1. Clean Water vs Grey Water vs Dirty Water
  2. The Application of the Water Pump
  3. The Size of the Dwelling using the Water Pump
  4. The Volume of Water Required
  5. The Type of Water Pump


A bit about Rainwater harvesting systems: they enable the collection and utilisation of rainwater from rooftops and other solid surfaces on a property. Harnessing this abundant resource gives you complete control over your own personal water supply whilst reducing reliance on mains water. A 2014 study by the CSIRO found that 96% of properties found their rainwater harvesting system to be beneficial, collecting an average of 42,000L each year. Cost-saving is but a small part of the value offered through rainwater harvesting, as you will be unrestricted in the use of your environmentally friendly rainwater reserves regardless of shortages or restrictions on mains water supplies.

1. The Water type passing through the Water Pump

To select the best water pump for your needs, you must identify the type of water you will be dealing with. The 3 key types are outlined below:
Clean Water is Drinking water, also known as potable water, is water that is safe to drink or to use for food preparation. Often sourced from mains water supply to homes. Meets AS4020 standards.
Greywater is typically water from rain collected off roofs as well as re-usable wastewater from washing machines, showers and other sources. Greywater replaces the need to use mains water for watering gardens or lawns and can potentially save thousands of litres of drinking water.
Dirty Water is typically water that contains small particles. Used for watering gardens or lawns which can potentially save thousands of litres of drinking water. Includes rain or greywater.

2. The Application of the Water Pump

Water Transfer pumps are built for use in multiple applications for water supply and the transfer of water. Applications include

    • residential homes
    • gardens
    • irrigation
    • farming

Water pumps are commonly with rainwater harvesting. Read more on this in the What Is Rainwater Harvesting section below.

3. The Size of the Dwelling using the Water Pump

What size household, or other dwelling, is using the water pump? A single storey dwelling will have different needs to a double storey dwelling.
Smaller homes will likely have less taps in use and thus would have different needs to a larger home, which would have more taps in use and various combinations.
Also, if you need to account for outside watering or irrigation you need to include this when considering the dwelling size for your water pump.

4. The Volume of Water Required

To understand the volume of water required within the dwelling that is running the water pump, you will have to work out the number of taps or outlets, both inside and outside, that are likely to be in use simultaneously.
Keep in mind that different outlets will have different flow rates.
To work out your household water flow rate you can measure the time it takes to fill a bucket from each tap or outlet. There is also the below table from AS/NZS 3500 - Australian National Plumbing and Drainage Part 1 – Water Supply.

Flow Rates at Fixtures or Appliances
The flow rates to fixtures, appliances, taps, valves and cisterns shall be not less than the flow rates specified below.
The maximum flow rate from a shower, basin and kitchen sink or laundry trough outlet shall not exceed 9 L/min.

Fixture / Appliance

Flow Rate L/min

Water Closet






Spray Tap




Sink (standard tap)


Sink (aerated tap)


Laundry Tub


Washing Mahcine


Hot Water System


Hose Tap (DN20)


Hose Tap (DN15)



5. The Type of Water Pump

When it comes to water pumps, there are a few types including Jet Pump, Multi-Stage Pump, Submersible Pump and Circulation Pump.

Jet Pump Powered by an electric motor that contains and drives an impeller/centrifugal pump. The impeller moves water, through the Jet Pump and increases the pressure of the water, to assist in areas where high suction lift is required (e.g. double storey homes).

Multi-Stage Jet Pump A centrifugal pump containing two or more impellers is called a multi-stage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. For higher pressures at the outlet, impellers can be connected in series. For higher flow output, impellers can be connected in parallel. Multi-stage pumps are quieter and ideal for applications where low noise levels are required.

Submersible Pump A submersible pump is a device which has a hermetically sealed motor close-coupled to the pump body where the whole assembly is submerged in a water tank or pit. The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between the pump and the fluid surface. Submersible pumps push fluid to the surface as opposed to jet pumps having to pull fluids. Submersibles pumps are more efficient than jet pumps.

Circulation Pump A circulation pump is a specific type of pump used to circulate hot water in a closed circuit within a house or apartment. They are very efficient because they only need to distribute liquid within a closed circuit to overcome the friction of a fixed internal piping system.

About Bromic Waterboy Water Pumps

With over 40-years’ experience, Bromic are experts in the manufacture and supply of quality plumbing products. Our range of pumps offers a complete solution for the transfer of water. Bromic Waterboy™ rainwater harvesting systems offer complete solutions for effective management of rainwater, with the ability to automatically supplement supply with mains water when needed for low-maintenance operation. We offer both submerged and external pump options in versatile configurations to fulfil the needs of all rainwater harvesting systems, big or small. The Waterboy Jet Kit and Waterboy Wizard™ Pack are specifically designed as complete solutions for pain-free installation and are both backed by Bromic’s industry-leading in-field warranty.