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Water recycling groundwater replenishment

About this lesson

This lesson helps senior students to understand what groundwater replenishment is, and the science that makes the water recycling process work.

Year level: 11, 12

Theme: Wastewater

Learning objectives

Students can:
  • Understand what groundwater replenishment is.
  • Increase knowledge of the science that makes the water recycling process work.

Curriculum links

Western Australian Certificate of Education WACE - General  

Earth and Environmental Science Unit 2

Activity 1 Outcomes: Science Inquiry Skills, Science as a Human Endeavour, Science Understanding 

Earth and Environmental Science Unit 2

Activity 2 Outcomes: Science Inquiry Skills, Science as a Human Endeavour


Western Australian Certificate of Education WACE – ATAR

Earth and Environmental Science Unit 3

Activity 1 & 2 Outcomes: Science Inquiry Skills, Science as a Human Endeavour

Earth and Environmental Science Unit 3 (Renewable Earth Resources)

Activity 1 & 2 Outcomes: Science Understanding

Integrated Science Unit 3 (Water resource and Sustainability)

Activity 1 & 2 Outcomes: Science Understanding


Australian National Curriculum - ACARA

Earth and Environmental Science Unit 3

Activity 1 & 2 Outcomes: Science Inquiry Skills, Science as a Human Endeavour

Earth and Environmental Science Unit 3 (Renewable Earth Resources) ACESES078

Activity 2 Outcomes: Science Understanding


Lesson description

Activity 1 Global groundwater replenishment – multimedia book

This activity aims to direct students’ research to explore the histories, technical processes and functionality of different groundwater replenishment and other recycled water schemes across the globe, presenting their analytical comparisons in the form of a multimedia book.

Use the ‘Groundwater replenishment’ fact sheet to introduce students to the groundwater replenishment scheme and process in Perth. In small groups, students research and investigate the differences and similarities between two global indirect potable reuse schemes such as groundwater replenishment schemes in Perth, Australia and Orange County, USA and one other established direct potable recycled water scheme e.g. Singapore or Windhoek, Namibia (see supporting resources section).

For each site, students should explore:

  • Historical context of the plant’s development. Why it was developed? Costs to build and maintain?
  • Community consultation and levels of acceptance
  • Geology and geography of the locations
  • Technology treatment processes – ultra filtration, reverse osmosis, ultraviolet disinfection
  • Current production percentages
  • How the water is (or will be) integrated into the supply system (direct or indirect, potable or non-potable)
  • Future plans

Multimedia book
A multimedia book is a way for students to display text, images, videos, audio files, and links to external sources of information to report on their findings. There are many programs that can be used. Here are a few top educational programs:

Using the collated information gathered from their research, students create a multimedia book to present a comparative analysis of the three groundwater replenishment plants they have explored. The booklet should include images, video, maps, models, and graphs to illustrate the various similarities and differences between the sites, while highlighting key factors, features and related technical pointers.
The final presentation is to be delivered by students in a face to face context, via classroom projector or smartboard.

Activity 2 Information brochure – groundwater replenishment

Groundwater replenishment is not something that everyone in the wider community is aware of. In this activity students will use research and data to inform about and advocate the use of recycled wastewater to replenish groundwater supplies.

Students will gather data and information on

  • Population growth in Western Australia
  • Water consumption in Western Australia
  • Rainfall or stream flow in Western Australia
  • Groundwater replenishment in Western Australia 

And any other sources that the student feels are relevant.  

The students will analyse this data and formulate conclusions about:

  • Why we need to replenish groundwater?
  • Whether the Western Australian climate is changing?
  • What water supplies will a changing population need?
  • How other water sources are coping with changing climate and population?
  • Do Western Australian people know enough about their water supply?
  • and any other relevant questions.

Once the students have collected their data and come to some conclusions they will need to present their findings in a brochure format. This needs to be appealing, eye-catching and informative for the average person.  Include graphs, picture and tables where necessary.

Sources of information

The following are some useful starting points for information gathering on our website:

Reflect & summarise

Extension activities

Teacher background information

Water recycling
Water recycling is a general term for the reclamation, treatment and reuse of water for new purposes. Recycled water can refer to water sourced from wastewater, greywater, groundwater, stormwater and rainwater for a variety of purposes, such as:

  • drinking water;
  • irrigation of recreation grounds;
  • groundwater replenishment;
  • industry
  • irrigation of non-food crops;
  • household toilets; and
  • laundry.

Regardless of the source, water to be recycled must be fit-for-purpose, which means that it must be treated to an appropriate level for its intended final use.

For the purpose of this booklet, the recycled water we refer to will be from wastewater sources.

Water recycling is essential to maintaining a reliable, sustainable and safe water supply for Western Australia and is a key part of Water Corporation’s climate resilience strategy. Increasing the amount of water that is recycled is crucial to managing our precious drinking water resources efficiently and making the most of our wastewater resource that is often ‘wasted water’.

Groundwater replenishment
Groundwater replenishment is the process by which secondary treated wastewater undergoes further advanced treatment to produce water which is safe to drink and meets Australian guidelines for drinking water. At this point it is then recharged into an aquifer for later use as a drinking water source. 
Groundwater Replenishment Trial (GWRT)
Water Corporation ran a three year trial of groundwater replenishment from 2010-12. It consisted of operating the Advanced Water Recycling Plant (AWRP) located on the same site as the Beenyup Wastewater Treatment Plant (WWTP), in Craigie, and then recharging the recycled water into the Leederville Aquifer on the site. 

During the trial plant’s operation 85,644 water quality  samples were taken. This included samples taken throughout the treatment process, at the point of recharge and groundwater samples. All of these samples consistently met stringent health and environmental guidelines. In addition to this, it was vital that we gained community support of groundwater replenishment in order for the trial to be a success and various community engagement initiatives were developed to gain community acceptance (see fact sheet ‘The value of community acceptance for groundwater replenishment’ for further details). 

The success of the trial has meant Water Corporation is now embarking on the development of Australia’s first full-scale groundwater replenishment scheme.

Groundwater replenishment process
Before wastewater reaches the AWRP, it undergoes biological treatment at the Beenyup WWTP to make the water suitable for both discharge to ocean, and for further treatment for recycling purposes. The wastewater treatment process removes some chemicals and micro-organisms, such as bacteria. It also removes most nutrients, detergents, oils, pesticides and heavy metals.

Treated wastewater that reaches the AWRP undergoes further multiple treatment processes which include:

 Step 1 – Ultra filtration

 Step 2 – Reverse osmosis

 Step 3 – Ultraviolet (UV) disinfection 

These treatment measures remove chemicals and micro-organisms in accordance with Australian guidelines for drinking water. Throughout the treatment process, water is continually monitored to ensure water quality is met.

At the end of the AWRP treatment process, water is recharged into groundwater 120 to 220 metres underground, into the confined Leederville aquifer and 754 metres into the Yarragadee Aquifer.

The Groundwater Replenishment Scheme
Stage 1 of Australia’s first full-scale groundwater replenishment scheme is planned to have the capacity to recharge 14 billion litres of recycled water annually. Subsequent stages will see the scheme ultimately deliver around 28 billion litres per year. By 2060, it is possible groundwater replenishment could contribute up to 115 billion litres each year by recycling water from Perth’s major wastewater treatment plants. This could account for up to 20% of total annual drinking water supply.

Groundwater replenishment around the world

Perth’s groundwater replenishment technology was based on that of Orange County, California (USA). Orange County Water District has been using a similar approach since the 1970s. Other water recycling schemes that supplement drinking water supplies also exist in Singapore, Hampton (England) and in Windhoek (Namibia). Since 2003, Singapore has mixed approximately one percent of recycled water with dam water for drinking. However, in Perth, groundwater replenishment returns the recycled water to deep groundwater reserves for storage, rather than directly into a dam or water pipes used for public drinking water supplies. The groundwater is then abstracted some years later, treated as per standard groundwater treatment processes and added to the drinking water supply.

Approaches to potable reuse
Drinking water or potable water is water safe enough to be consumed by humans or used with low risk of immediate or long term harm. The recycling of water from wastewater for drinking can be referred to as either direct or indirect potable reuse. There is some debate regarding the interpretation of direct and indirect reuse, however we have summarised the definitions as defined by the Australian Department of Health and Aged Care.

Direct potable reuse can be defined as either the injection of recycled water directly into the potable water supply distribution system. Injection could be into a service reservoir or directly into a water pipeline and therefore the recycled water used by customers could be either slightly diluted or undiluted. There are no current examples of direct potable reuse in Australia. Internationally, the nearest example is in Singapore where they have branded their recycling program NEWater. NEWater is primarily for non-potable industrial uses but a small percentage of NEWater is mixed with raw water in the reservoir before treatment and then supplied to customers as tap water. 

Indirect potable reuse can be defined as recycled water returning to the water cycle a significant distance upstream of the water treatment plant. This distribution could be into a major water supply reservoir, a water source which feeds a reservoir, or into a water supply aquifer. This recycled water would likely be greatly diluted with other ‘natural’ water before its next use.

Indirect reuse provides a separation between the treatment plant and the next user. This type of potable reuse is currently a more acceptable approach for the community as it depends to a lesser extent on the reliability of technology, and incorporates ‘natural’ processes within the reuse system to improve the perceived water quality.

Supporting Resources

Water Corporation
For further information search:

Other organisations websites
The following organisations may also be able to provide resources:

  • Groundwater replenishment system – purification steps
  • PUB Singapore’s national water agency – NEWater
  • Earth magazine – Drinking toilet water
  • Department of Health and Aged Care – Review of health issues associated with potable reuse of wastewater
  • Nabia water reuse 

Did you know?

Key vocabulary