Teaching sequence

Lesson objective

In this lesson students investigate how and why water is purified in a water treatment process, identify the role science has played in developing the treatment processes and compare the water cycle and water treatment processes.


Review the ‘water cycle’ and ask the students this question: If water is renewable, why is it necessary to have water treatment plants? Discuss the impact of increasing population and pollution on the sustainability of water supplies for human consumption and use.


  1. Display the image of water treatment process Describe each of the steps. Ask students to relate the steps to the water cycle and to the separation techniques they have learnt about.
    Water treatment process.
  2. Discuss why water treatment is important in relation to drinking water
  3. Ask students to engage with the learning objects Making water drinkable: water treatment and Making water drinkable: colloids.
  4. Discuss how science is central to producing clean water through the development and advancement of water treatment processes.
  5. Model water treatment processes using the downloadable activity Water filtration


Engage with the Water Island game to encourage the students to consider sustainability of water.

Lesson Resources


Student activities

Digital resources

L3103 Making water drinkable: water treatment, NDLRN

L3104 Making water drinkable: colloids, NDLRN

Water Island game, seqwater


Water filtration activity, US EPA (PDF, 193 KB)

Extension activities

How can water be made safe to drink? (Word 1.18 MB)

Useful links

L3105 Making water drinkable:
water cycle jigsaw
NDLRN. Learning object

L18 Explore water pipes, NDLRN

Water purification,
WaterSecure. Information. The original resource no longer exists, this copy made available through the Internet Archive's Wayback Machine.

Water filtration,
US EPA. Learning object