When it comes to fresh drinking water, Hong Kong has never had many options beyond sourcing most of it from Guangdong. The city spends billions on water piped in from the Dongjiang through pipes that first stop at a treatment plant in Shenzhen. The system, built only recently and at great cost to taxpayers here, is meant to protect Hong Kong's water supply from the industrial waste and sewage that is being constantly pumped into the river. However, as shown by testing conducted periodically by green groups - and now the news that Guangdong intends to build a toxic waste plant in the catchment area where the pipe begins - questions over water quality are far from settled. Area residents have told Hong Kong's Green Power the plant will include landfill and incineration for electronic waste, batteries and possibly medical waste. That Hong Kong has not been told of the plans yet is shocking, and environment secretary Sarah Liao Sau-tung is right to be seeking details from across the border. Claims that the project will meet international standards are undercut by its closeness to the river and the hazardous nature of the material to be processed. The potential danger from seepage is clear and the immediate priority has to be finding out what the plans are, what safety control measures will be in place and whether alternative locations can be found. The news highlights yet again the need for a regional water management strategy, one that includes the much-abused Pearl River Delta. Pollution problems over the border involve Hong Kong companies and eventually affect Hong Kong residents in one way or another. The impact on Guangdong residents and environmental quality north of the border is also unquestionable. Under the current arrangement, it could well be far too late by the time Hong Kong learns about projects such as these. In fact, an environmental impact assessment and consideration of alternative sites has already been conducted. Getting the province to reverse its plans at this point will be much more difficult than earlier in the process. Without extensive environmental co-operation and consultation - which could take years to accomplish - Ms Liao's department should be seeking guarantees on the quality of water from the Dongjiang and upstream protection from toxic hazards. If minimum standards and prohibition of contaminating projects near the catchment area are not already written into water supply contracts, perhaps they should be. Hong Kong may have limited choice on where its drinking supply comes from, but it should insist on the highest quality and cleanliness standards. If the consequences of such a policy include a cleaner environment for Guangdong residents, all the better.