The steering board has asked permission from the municipal People's Committee to conduct research on the feasibility of the proposal.

Nguyen Trung Viet, head of the city's Climate Change Bureau, was quoted as saying in Sai Gon Giai Phong (Liberated Sai Gon) newspaper that rainwater in HCM City contained few toxic substances and was basically clean.

The rainwater was relatively clean because most of the city's 500,000 automobiles meet the Euro 2 gas emission standards, he said. The city has more than 5 million motorbikes, but the bikes have small engines and do not emit much exhaust.

The rainy season in the city lasts six months a year, with an annual rainfall of 1,800 -2,200mm. In recent years, climate change has increased the number of rains as well as rains with more than 100mm of rainfall.

With the increase in population, the demand for clean water for household use has increased.

The second phase of the Sai Gon River Water Plant with a capacity of 300,000cu.m a day is already underway.

Under the board's proposal, rainwater would be used to irrigate plants and clean houses. Later, if the rainwater is filtered and preserved properly, it could be used like tap water.

Flooding in HCM City has also been caused by old, inefficient water drains in three of five basins. The water drainage systems of Nhieu Loc-Thi Nghe, Tan Hoa-Lo Gom and Tau Hu-Ben Nghe canal basins, for example, were designed to handle rains that have a rainfall of 75mm over a three-hour period. However, the number of rains has increased.

The three basins account for 70 per cent of the city's area.

Le Hoang Minh, deputy head of the city Department of Transport's Flooding Prevention Division, said rainwater collection would not be easy.

He said that it would be easier to place the containers for rainwater under homes or in yards, rather than on house roofs.

To encourage people to collect rainwater, the city should develop policies to support households who build containers, he said.

Ho Long Phi, director of the Centre of Water Management and Climate Change under the Viet Nam National University of HCM City, agreed that rainwater collection could help reduce flooding.