The country has 43 wastewater treatment plants with a capacity of 926,000 cubic meters of wastewater per day, the report said, quoting Vu Ngoc Anh, head of the Ministry of Transport's Science, Technology and Environment division.

But "challenges in collecting and treating wastewater" keep the treatment rate low, he added.

Hanoi has six operational plants that treat a total of 276,300 cubic meters of wastewater per day, amounting to just 22 percent of its daily discharge. The city says work on new wastewater treatment plants in the city are far from complete, and 12 more are on the anvil. Difficulty in finding private funding for drainage systems is a factor in the tardy progress, the city is cited as saying by the report.

Ho Chi Minh City, meanwhile, has three operational plants and other local facilities that treat a total of 370,624 cubic meters of wastewater per day, about 21.2 percent of its total daily discharge.

The report also quoted Nguyen Viet Anh, director of the Institute of Environmental Science and Engineering (IESE), as saying that most ODA funded projects do not have the component of connecting the drainage system with urban households, posing a "major challenge" to establishing efficient drainage and wastewater treatment systems.

"Saving energy and finding alternative energy sources to collect, treat and reuse wastewater is a major issue that attracts a lot of attention. Mastering energy management in collecting, treating and reusing wastewater is a strategic investment that brings high and sustainable economic efficiency," said Anh.

Only 60 percent of households in Vietnam are connected to public water systems, and only 10 percent of collected wastewater being treated, said a World Bank report on urban wastewater management in Vietnam. The country would need about $8.3 billion to provide drainage services for its 36 million urban citizens in 2025, the report said.

Water pollution is one of  top five concerns to Vietnamese public, according to a study by market research firm Indochina Research, after air pollution, food safety, sexual harassment and healthcare.