HCM City's Department of Natural Resources and Environment plans to use Global Positioning System to monitor the movements of waste tankers after finding that as much as 80 percent of household sewage is being dumped into rivers and canals.

The department said between 200-240 cubic metres of sewage is being dumped into public water sources every day.

The city has about 125-150 tankers collecting toilet waste in the city. However, only Hoa Binh Waste Processing Ltd Co in Binh Chanh district is able to treat sewage.

Le Tien Dung, the company's director, said the firm in 2008 invested 13 billion VND (685,000 USD) in building a waste-treatment facility that could handle 300 cubic metres of sewage a day. However, the plant typically receives just 25-30 cubic metres of waste daily, Dung said.

Instead of transporting the waste to the plant, drivers have been pouring it into canals and rivers, which are now badly polluted and posing a threat to residents' health.

Just last week, the city's environmental police found a tanker illegally dumping toilet waste into the waterway near Tan Phu Trung Industrial Zone in Cu Chi district.

Police said tankers could completely empty their loads in just three to four minutes, making detection difficult.

The Department of Natural Resources and Environment said electronic chips would be fitted to tankers so that their movements could be monitored.

Nguyen Trung Viet, the department's solid waste division chairman, said chips would be fitted to all tankers by early next year./.