Mission: Tokyo

摘要

In October last year I led a Department of Trade and Industry sponsored Scientific Mission to Japan that looked at water recycling and reuse in the Tokyo region. The trip was organised by British Water, the trade association, and the six-member team included representatives from water utilities, a supply company and the Environment Agency. To give an example of how seriously water reuse is taken, since the 1980s all buildings in Tokyo constructed with a floor area of more than 30,000 m2 must recycle rainwater and reuse greywater, i.e., water from sinks, baths and showers. This means that most large buildings in Tokyo have treatment plants in their basements. Does this mean that Tokyo is dry? No - on average, the city receives about 1600 mm of rainfall per year compared to an annual precipitation of about 600 mm in London. But it is undoubtedly a large, crowded urban sprawl, Greater Tokyo being the world's largest conurbation with a population of 26.5 million in 1994.