# Maths KS2: Understanding how rainwater can be harvested using maths

In Ecomaths, Stefan visit a huge hi-tech greenhouse in Kent that grows cucumbers all year round.

He meets Judy Whittaker who explains how they harvest water from the roof of the greenhouse, collect it in a reservoir and use it instead of tapwater to water their plants.

In a demonstration, Stefan pours water from one container into another to explain how the same volume of water can come in lots of different shapes.

Using a metre square frame he shows that for every millimetre of rain that falls on a square metre or roof we get a litre of water.

Rob James helps him calculate how much water can be collected from the greenhouse roof that is 61,000 square metres.

Stefan finds out that it depends on the rainfall but on average is 35 million litres per year.

Stefan then meets a group of children from Peatmoor Primary School who talk about the water they need for their big ecogarden and show him their own rain harvesting project using the garden shed.

Next Stefan helps them to calculate how much water they can collect from their main school roof using a scale plan of the school.

This clip is from the series Ecomaths.

### Teacher Notes

Students could investigate how much water they could harvest in their school.

Students could work out the measurement of the school roof using a scale drawing of the school or by measuring the external walls.

They could find the monthly and annual rainfall in the local area from the internet in order to calculate how much rain could be harvested.

How big would the school water storage tank have to be?

What would the size of the water storage tank need to be for a month, or a year?

Students could also research uses for the collected water within the school.

### Curriculum Notes

This clip is suitable for teaching Maths at KS2 in England, Wales and Northern Ireland and 2nd Level in Scotland.