Every week brings a new story of environmental decay in this region and elsewhere in the world. There are so many examples of the polluted nature of the planet that it comes as no surprise that the territory's water supply is also now in danger. The mainland is developing at a daunting speed. As mountains are flattened, paddy fields buried in concrete and a new metropolis spreads across the borderland, the Dongjiang river - or East River - from which most of our water is obtained comes under pressure as never before. Matters are made worse because the depleted farmland is required to produce extra food, so more chemicals are poured into the soil. Despite assurances from the Water Supplies Department that heavy metals are not a problem, environmentalists insist they find their way into local drinking water, producing an unsavoury cocktail of sewage and chemicals. Factories, piggeries and housing estates line a river which in 1995 absorbed 779,000 tonnes of chemicals and 21,000 tonnes of pesticides. Without being alarmist, it is obvious that something needs to be done. China prosecutes industries which pollute, but as the population explodes, the greater problem is untreated sewage. Surveys also reveal that mercury, arsenic, lead and other poisons leave their traces in the river. If, as we are told, there is not a danger now, this does not mean our water will not be at risk in the near future. Therefore, a strategy must be devised between authorities on both sides of the border to clean up the river. The fact that Hong Kong has the facilities to turn this hazardous brew into something drinkable is small consolation. The process is a drain on taxpayers' money and resources. There is also a limit to how much chlorine can be poured into the water to kill harmful bacteria. Scientists are still not sure what effect large amounts can have on the human body. Experts in Hong Kong and China are concerned about the deteriorating state of the East River, and this obviously requires a dual approach. At present, Hong Kong is buying sub-standard goods from the mainland, and is paying double for them because of the money spent transforming it into drinkable water. Unilaterally, the Government should be devising a conservation programme for the territory's own limited supplies in case a real emergency arises. It should also encourage people to be sparing in their use of this most precious commodity. Agriculturalists can show farmers how to feed the soil without filling it full of chemicals. Much of this pollution is totally unnecessary. None of it is acceptable.