There was a time when the idea of granting floor-area concessions to developers of housing estates in return for recycling of rainwater and household waste water for toilets and gardens may have met with universal approval. But times have changed. News that the government is studying the idea has had a mixed reception. This is because developers have exploited an existing deal that already gives concessions for including supposedly 'green' features in estates such as clubhouses, podium gardens and car parks. These are excluded from the gross-floor-area (GFA) calculation, which enables them to build more flats, resulting in towers that obstruct air flow. The government is reviewing the scheme after it was found some had used it to almost double the size of their projects. Lawmaker Lee Wing-tat, the Democratic Party's housing spokesman, says there is consensus in the community that developers should not get any more concessions for 'green' features. But Green Sense chairman Roy Tam Hoi-pong is prepared to make an exception because the proposal is genuinely green. Secretary for Development Carrie Lam Cheng Yuet-ngor says a government consultant is studying a system that saves rainwater and treats water from the kitchen sink and bath. It is already being tested in some new government buildings. Officials have told lawmakers that two blocks of 30 storeys would need a 1,000-square-metre basement to house it. They say it will be considered in particular for areas holding 20 per cent of the population that still use fresh water instead of seawater for toilet flushing. Tam has a point. Water recycling is not to be compared with clubhouses, which he has previously described as 'these huge and unnecessary structures [that] block air flow'. They have also resulted in the provision of fringe amenities that do not add environmental value. He is right to say that developers should use their own floor areas for such facilities, rather than as an expedient means of making more money out of a greater number of ever-smaller flats. But Lee has a point too when he says the government should be very cautious in granting any more floor-area concessions. Ironically, the idea has been floated as the government is completing a review of the decade-old GFA concession policy. What sets it apart is that it would save public money that would otherwise be spent for the extension of the seawater system to unserviced areas, and conserve water. Cost is a factor in practicality, because Hong Kong has access to cheap water supplies from the mainland. If developers are to continue to receive GFA concessions in return for 'green' features, the environmental benefits to the community should be as real as the increased profits are to them. In that respect, water recycling could at least set a good example to adopt as a benchmark, so long as it did not add to the bulk of a building. That would rule out clubhouses in new housing estates of hundreds of thousands of square feet - even one million square feet in one instance. As we reported earlier this week, developers have gone to extreme lengths to fill them, including rooms for cigar smokers, bands and pets, a Thai boxing ring and even a zoo. The green features deal has too often delivered more tangible benefits to developers than the community. Water recycling may be an exception. But there is an argument that if it is good for the environment and found to be practical, it should be mandatory, not an option for profit. The community should not have to pay for it through sacrifice of government land premiums.