Using rainwater or handwashed water for flushing, instead of clean treated water from PUB, the system is able to save about 2.5 litres of water with every standard flush, North East CDC said in a press release on Friday.

'PUB can also save cost by treating less water. The only cost for the project is the solar panel. But users can use the solar panel for other uses such like operating their of air-con and lights. This will also reduce the electricity they use and cut cost,' 11-year old Paya Lebar Methodist Girls (Primary) student Grace Lee said.

The 'green' flushing system is one of 22 projects submitted by students for the North East Schools Go Green Competition organised by the North East CDC and supported by the National Environment Agency. Other projects include a Recycling ATM, which dispenses money when a bottle is deposited for recycling.

Residents from the North East CDC will vote for their favourite green project.

The projects will be on display at Compass Point Shopping Mall from March 8 to 15.