Students from 21 secondary schools and the Singapore Polytechnic will take turns to clean the reservoir, Singapore's 15th, which opened in November last year. They will also test for the quality of the water, for example its acidity levels.

The event on Sunday was a prelude to the Singapore International Water Week beginning Monday.

Guest-of-honour, Dr Teo Ho Pin, the mayor of North West Community Development Council, said: 'We have to educate Singaporeans from young on the importance of sustainability development and the environmental impact of the choices they make. The Government's efforts alone are inadequate. We need a 'whole of nation' effort to make Singapore a more sustainable city.'

Sunday's festival was attended by about 10,000 people who got to take part in activities such as dragon boat and raft races, races on solar-energy boats and walking on water using shoes made of special foam.

Singapore Polytechnic also handed a $50,000 cheque to deputy Straits Times editor Alan John for the newspaper's School Pocket Money Fund which raises money for financially strapped children to pay for meals at school, transport fare or stationery.

'During this economic downturn, school going children may face hardship. So we decided to give to the ST School Pocket Money fund because it has a wider spectrum of school going kids,' said Mr Lim Cher Yam, director of the polytechnic's School of Architecture and the Built Environment who is also chairman of the Singapore International Water Festival.