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Let's debate! Groundwater replenishment

About this lesson

Students research groundwater replenishment and debate a topic on the issue.

Year level: 5, 6, 7, 8, 9, 10

Theme: Wastewater

Learning objectives

Students can:
  • understand what groundwater replenishment is
  • research groundwater replenishment issues relevant to the debate topic
  • refine vocabulary and use speech and debate techniques in the classroom
  • develop, rehearse and deliver an argument for or against the topic
  • use interaction skills to communicate ideas clearly and persuasively.

Curriculum links


  • Clarify understanding of content as it unfolds in formal and informal situations, connecting ideas to students’ own experiences and present and justify a point of view ACELY1699
  • Use interaction skills, varying conventions of spoken interactions such as voice volume, tone, pitch and pace, according to group size, formality of interaction and needs and expertise of the audience ACELY1816
  • Use interaction skills when discussing and presenting ideas and information, selecting body language, voice qualities and other elements, (for example music and sound) to add interest and meaning ACELY1804
  • Use interaction skills for identified purposes, using voice and language conventions to suit different situations, selecting vocabulary, modulating voice and using elements such as music, images and sound for specific effects ACELY1808
  • Use interaction skills to present and discuss an idea and to influence and engage an audience by selecting persuasive language, varying voice tone, pitch, and pace, and using elements such as music and sound effects ACELY1811
  • Use organisation patterns, voice and language conventions to present a point of view on a subject, speaking clearly, coherently and with effect, using logic, imagery and rhetorical devices to engage audiences ACELY1813

Things you will need

Lesson description


Select an argument/s to debate. Suggestions include:

  • Recycled water is not safe to drink and will taste funny.
  • We don't need to recycle water. We will never run out of fresh water.
  • The water cycle cleans water naturally, we don't need to do anything.
  • If nature can no longer recharge our aquifers in the South West of WA, then we must.
  • For decades some countries have been drinking their treated wastewater or adding it to groundwater. We should too.
  • We are taking water out of our aquifers all the time, it is up to us to put water back in.


  1. Before the debate students discuss and agree success criteria and a voting mechanism to select winners (E.g. show of hands, voting slips, use of interactive whiteboard etc.). This is then developed by a class member.
  2. Students are divided into groups of 4 and allocated a side either for (affirmative) or against (negative) the argument.
  3. Groups start to prepare and research (use the relevant Debate for against activity sheet).
  4. Groups practice and refine their debates.
  5. Groups deliver their debates.

Reflect & summarise

  • Students vote for the winners of each debate based on the success criteria created.
  • Ask students what they think about groundwater replenishment as a future water supply for Perth?

Teacher background information

What is groundwater?

Groundwater is made up from rain which percolates down through the rocks and soils and into aquifers. Aquifers are composed of sand, sandstone and limestone. In Perth there are 3 layers of aquifers:

  1. Superficial aquifer: The shallowest aquifer which stretches across the coastal plain. Superficial aquifers are located close to the surface and often express themselves as wetlands or lakes.
  2. Semi-confined Leederville aquifer: Below the superficial aquifer, and is separated by confining layers which minimises water movement. The Leederville aquifer is often several hundred metres thick, and in some areas it connects with the surface.
  3. Confined Yarragadee aquifer: The oldest aquifer that provides a robust supply of groundwater even in dry years because of its vast storage and limited connection to the surface environment. It extends from Geraldton in the north to Albany in the south.

What is groundwater replenishment?

Groundwater replenishment is an innovative concept where treated wastewater is further treated to drinking water standards and recharged into groundwater supplies. The water is then stored and taken out some time later for further treatment and supply to a drinking water system.

Before wastewater reaches the Advanced Water Recycling Plant, it has already undergone rigorous treatment at the Beenyup Wastewater Treatment Plant to remove chemicals and micro-organisms such as bacteria, nutrients, detergents, oils, pesticides and heavy metals.

At the Advanced Water Recycling Plant it undergoes further treatment processes which include ultrafiltration, reverse osmosis and ultraviolet disinfection before it is recharged into the ground. This removes chemicals and micro-organisms to meet World Health Organisation standards and Australian guidelines for drinking water.

There are several water quality checkpoints (known as critical control points) throughout the treatment process to ensure each stage of the plant is working at optimum levels.

If water does not meet the required standard when it reaches a check point, it triggers an alert for action to be taken. For example, we may need to divert the recycled water back to the Beenyup Wastewater Treatment Plant or temporarily shut down the plant.

As WA continues to experience a drying climate and an increasing population, demands on our water supplies are greater than ever. Groundwater replenishment could help Perth by:

  • reducing our dependence on rainfall as a source of water
  • ensuring ‘climate resilience’ by recycling water on a large scale
  • potentially providing up to 20% of Perth’s drinking water supplies by 2060 (if expanded to our other major wastewater treatment plants).

We have a 4 part video that will help your students better understand why groundwater replenishment is important to WA.

Did you know?

Groundwater from the Groundwater Replenishment Trial in Perth (Craigie) has moved an average of 100 metres per year. Usain Bolt runs this distance in less than 10 seconds.

Key vocabulary

  • Aquifer: An underground layer of rock or sand that can absorb and hold water.
  • Confined aquifer: A deep aquifer that is confined by low permeability material such as clay, minimising water movement between aquifers.
  • Filtration: The act of removing particles held within a fluid by passing it through a filter.
  • Groundwater: Water located beneath the ground surface in soil pore spaces and in the fractures of rock formations.
  • Replenishment: To fill or build up again.
  • Reverse osmosis: The movement of water from low concentration through a semipermeable membrane to an area of higher concentration when pressure is applied to the solution.
  • Semi-confined aquifer: Below the superficial aquifer, and separated by confining layers which minimises water movement however in some areas it connects with the surface.
  • Stormwater: Rainwater which has run off roads, roofs, paved areas etc. and is conveyed by constructed drains leading to waterways.
  • Superficial aquifer: An aquifer located close to the surface, often expressing itself as a wetland or lake.
  • Wastewater: Water that has been used inside a home, business or industry that travels to a wastewater treatment plant.
  • Wastewater system: The system that collects wastewater from households, commercial businesses and industries, directs it to treatment plants, treats it to an environmentally accepted standard before being reused or safely discharged back to the environment.