About this lesson
Students conduct a survey then research and write a report on how their school could save water through the use of water efficient dual-flush toilets.
- understand how to save water through the use of dual-flush toilets
- create, trial and conduct a survey to collect data and create a graph
- write a report to the Principal using appropriate structure and including data displays.
- Identify questions or issues for categorical variables. Identify data sources and plan methods of data collection and recording ACMSP068
- Collect data, organise into categories and create displays using lists, tables, picture graphs and simple column graphs, with and without the use of digital technologies ACMSP069
- Select and trial methods for data collection, including survey questions and recording sheets ACMSP095
- Construct suitable data displays, with and without the use of digital technologies, from given or collected data. Include tables, column graphs and picture graphs where one picture can represent many data values ACMSP096
- OI.9 - Sustainable futures result from actions designed to preserve and/or restore the quality and uniqueness of environments.
Things you will need
- Toilets at school activity sheet
- Bucket filled with 20L of water
- Bucket filled with 4.5L of water
- Bucket with litres marked on it (optional)
- Marker pen (optional)
- Why do we need to save water?
- How do we use water at school?
- How could we calculate how much water our toilets currently use?
- How many litres of water do you think our school toilets use each flush? Estimate and write on the board.
- Show students the two buckets of water to demonstrate the difference between 20 litres (old style single flush toilet) and 4.5 litres (full flush using the most water efficient dual-flush system).
Part 1 – Investigate toilets at school
- Get students to use the example on the activity sheet to calculate the amount of water used in single and dual-flush toilets, then investigate how many toilets are at school and whether they are single-flush or dual flush.
- If the school has dual-flush toilets determine what capacity the toilets are. To do this:
- Mark the water level inside the cistern.
- Turn off the tap to the toilet and flush it.
- Using a bucket fill the cistern back up to the water level.
- Record the number of litres used to fill it.
- How water efficient are the school toilets? Was the previous estimate correct?
Part 2 – Toilet survey & report
- Students collect data by creating a survey to find out how many times the toilets at school are flushed during one day and how often students use the full-flush or half-flush option. Note: Urinals are excluded from the survey.
- Students’ trial their survey questions and recording sheets on a fellow class member and amend accordingly.
- Students survey another class and display their data findings in a graph.
- Estimate results for the entire school.
- Work out how much water could be saved a day, a week, a year, five years and 10 years if the school:
- converted any single-flush toilets to the most efficient 4.5/3 dual-flush systems
- upgraded older style dual flush toilets to the most efficient 4.5/3 systems
- educated all students and staff on the proper use of dual flush systems.
- Organise for your students a quote from three plumbers to replace single flush toilets with the most efficient dual-flush toilets.
- Students write a report for the Principal detailing the water that could be saved by changing the school to the most water efficient toilets. Include data displays showing research and survey results (including water and cost savings).
Reflect & summarise
- How much water do our toilets use every day?
- How much water and money could we save by changing the school to water efficient toilets?
- Why do we need to save water?
- Develop an education program to educate students and staff at the school on how they can save water by using the dual-flush option (e.g. devise posters, stickers, prepare presentations, run fun educational events)
- Develop an educational assembly item linked to World Toilet Day – 19 November
- Investigate and report on worldwide standards of sanitation
- Investigate the most water efficient toilet systems currently available (e.g. 4, 5, 6 star models). For information see waterrating.gov.au
Teacher background information
Total water use for a school is based upon personal water use and outside water use. The volume of water used per school for different purposes can vary a great deal. Variables might include the use of scheme water for irrigation, the number of students, the use of air conditioners and whether the school has a pool.
Toilets use around 9% of total household water use. In a school setting replacing the toilets for more efficient models can bring considerable water and cost savings.
Water use of single flush and dual flush toilets
Full flush (litres)
Half flush (litres)
Older style cisterns (single flush toilet)
11 – 20
Older style dual flush
Newer style dual flush
More water efficient dual flush (WELS 3 star)
Water efficient toilets
Since the 1980s it has been a requirement that new buildings and renovations be fitted with water saving dual-flush cisterns. You can save money, energy and water by using a more efficient toilet or urinal.
Before purchasing a new toilet, check the water rating. The more stars, the more efficient the model. The star rating system is operated by WELS, Australia's water efficiency labelling scheme. It allows consumers to compare the water efficiency of different products. Guides and further information on the current water consumption of products is available from their website waterrating.gov.au.
Did you know?
Replacing a single flush toilet with a dual flush can save approximately 90 litres a day in your home.
- Cistern: A container that holds water for flushing out urinals and toilet bowls
- Conserve: Use cautiously and frugally
- Dual-flush toilet: A toilet with a half and full flush option
- Report: To communicate findings
- Scheme water: Supplied water that is drinkable
- WELS: Water Efficiency Labelling and Standards Scheme
Related links & other lesson plans
You might also be interested in...