Reclaimed water has been used for decades to relieve many cities over the world from the water shortage problem. Reclaimed water is commonly used for toilet flushing, landscape irrigation, water features, water-cooled air-conditioning, car washing, street washing, drain flushing, etc. It therefore has a high social value in being used for maintaining a pleasant and healthy environment for the community, even during times of fresh water shortage.

A reclaimed water supply system can be of various scales. In a municipal scale, it is attached to the centralised sewage treatment works. In the scale of a small district or a sizeable housing estate, reclaimed water systems can be constructed to treat the combined wash water and rainwater, with the rejected concentrates discharged into the sewage disposal system. Within a building lot, reclaimed water systems can also be constructed to better utilise the wash water and rainwater. 

In Hong Kong, seawater is used for toilet flushing, but it practically cannot be used for other purposes. There are actually pilot studies being conducted on the use of reclaimed water. The experience gained in these studies will certainly help the future development of reclaimed water supply systems in Hong Kong, especially in areas where seawater pumping is expensive to reach. This seminar will describe the alternative ways of using reclaimed water.