The Environment Bureau recently released Hong Kong's blueprint for sustainable use of resources for the 10 years to 2022, to deal with one of the city's burning issues - waste reduction - to recover valued resources after use and become a more sustainable society. However, the blueprint does not include the most critical and recyclable resource of all - our limited water resources. According to a Water Supplies Department survey on domestic water consumption, an average Hong Kong person showers more than once a day, and uses 55.2 litres of fresh water. The department has also estimated that approximately 90 litres of seawater is flushed away per person each day. Added together, every day 145.2 litres is used by the typical Hong Kong person to just shower and flush the toilet, roughly the same amount that a Chinese urban dweller uses for all purposes of their daily life. For a city that relies almost entirely on external water resources to fulfil its needs, such per-capita figures seem exorbitant. Some efforts have gone into raising public awareness on water conservation. While fresh water use has declined a little, water use for toilet flushing continues to rise. Clearly, current efforts are not enough. Last year, the department supplied 270 million cubic metres of seawater, mainly for toilet flushing. The amount of seawater could almost fill up the entire High Island reservoir. Additionally, 76 million cubic metres of fresh water are provided to those who could not access seawater for flushing, enough to fill up the Pok Fu Lam reservoir some 300 times. It seems perplexing that such volumes are expended, but it is even more disturbing that we do not actually know how much is being spent to supply seawater for toilet flushing. Official government expenditures offer no clue on the cost of seawater supply and treatment. All costs involved in drawing, filtering, distribution and mostly treating flushed water are "invisible" because they have been covered by the government. These services cannot be free of charge, even if we do not have to buy seawater from mainland supplies as we do drinking water. Without official numbers, I have made some rough estimates. The department once stated that the cost of seawater supply was roughly 30 per cent that of our fresh water supplies. Currently the fresh water from Dongjiang in Guangdong costs Hong Kong HK$8 per cubic metre, so roughly the 270 million cubic metres of seawater used last year cost about HK$648 million. For waste water treatment, the Drainage Services Department is estimated to have spent HK$622 million last year to treat seawater after it went down to the drains. In total, HK$1.27 billion was spent last year. This is no small sum, so shouldn't we attempt to squeeze more, in terms of water resources, out of every cent we spend? The government should get its act together, and thoroughly examine Hong Kong's water resources from a life-cycle cost point of view. Seawater and waste water should be viewed as resources, to form an integrated sustainable water-use policy. The government should begin a review process. It is taxpayers' money after all, and Hong Kong people have the right to decide what to do with it. Su Liu is head of Greater China and water policy research at Civic Exchange