Some parents were aghast, but they warmed to the idea when they saw that their children, at the Dnyan Ganga School, were discovering the wealth hidden within waste. Today, the school has a miniature worm composting (vermiculture) pit, a lush row of plants fed on what it churns out, scores of happy parents whose kitchen waste has been used, and a clutch of students who stride about officiously after class hours, to check if anybody has left behind any litter.

The students' sense of environmental responsibility rubs off at breakneck speed on their peers. They are part of the CLEAN-India (Community Led Environment Action Network) campaign, a massive nationwide attempt to monitor and measure environmental degradation - and then spread the word that there's much to be done. The brainchild of a branch of Development Alternatives, based in New Delhi, it is at work in 35 schools in and around India's capital plus others in 34 cities all over the country.

As soon as the Dnyan Ganga students returned from their Diwali vacation in November, they began scouring Pune's busiest highways, water bodies, public taps and civic water pipelines armed with monitoring kits provided by CLEAN-India. The water-testing kits monitor 14 parameters for water quality including marking off levels of physical, biological and chemical components.

Similar air-testing kits, also used by school students, monitor suspended particulate matter, sulphur dioxide and nitrogen oxides in ambient air. The results from both monitoring exercises go to Development Alternatives' TARA laboratory on the outskirts of New Delhi, a modern research unit, packed with sophisticated equipment.

The findings are always worrying. This monsoon, students from New Delhi schools collected water samples from household taps, groundwater sources, handpumps and even slum areas and found frightening problems with the capital's drinking water. It contained ammonia, bacterial contamination - coliform, which indicates the water has been contaminated by human or animal faeces and causes a host of waterborne diseases - and nitrate values well above permissible norms.

Tests by CLEAN-India students across the country in early 2003 found that in 19 cities - from Pondicherry in the south to Dehradun in the north - at least half the drinking water supplies they tested were polluted above permissible limits.

Colonel V Katju, who manages the programme, says that students 'interact with decision makers' and are catalysts for change. 'They will not rest until their voices are heard and remedial action is taken. From schools to communities, townships, districts, states and regions, a network of like-minded groups is created, fostering cooperation and community action.'

In Shillong in northeast India, a group of children cleaned a stream and convinced the local people not to dump their waste into its sluggish waters. At a school in Noida, near Delhi, students went straight to the management with test results showing bacterial contamination in their drinking water. A filter was installed to exclude it.

Colonel Katju says the students' greatest achievement is in changing people's mindsets and in helping to bring about policy changes like the use of natural gas for public transport, utilizing domestic waste for manure, creating green areas, and getting ecologically harmful practices banned. In the process, they also create a set of trained future citizens who care for the environment.