Singapore is another excellent example. Apart from importing fresh water from abroad, the city-state ensures an adequate water supply by collecting almost every drop of rainwater in catchments.

It took Paris one and a half centuries to complete the 2,400 kilometers of drainage tunnels and more than 6,000 underground reservoirs that serve the city's needs today.

In contrast, the drainage system of central Beijing has only been tinkered with now and then when necessary since Ming Dynasty (1368-1644). Moreover, the city mainly relies on several small reservoirs in the mountainous areas to the north and its nearly depleted groundwater to satisfy its exploding demand for water.

Only one out of 49 underpasses in Beijing, Fuxingmen underpass, is equipped to collect rainwater. As for the will-be-built catchments, insightful and meticulous calculation is needed to match them with the existing drainage system and rainfall levels, because holding water is self-evidently more difficult than draining it.

Building more underpass water catchments will not only ease the city's traffic nightmares during the rainy season but also enable this valuable natural resource to be used to quench the thirst of the water-guzzling metropolis.

It is a good beginning, but Beijing still has a long way to go to ensure it makes the most of its rainwater.

China Daily

(China Daily 07/20/2011 page8)