Nguyen Ngoc Ly, Director of the Hanoi-based Centre for Community and Environment Research said rapid urbanisation and industrialisation were generating more and more pollutants, and the water environment had been badly hit.
Apart from the economic losses, water pollution had had serious health impacts, she said.
Fixing water pollution required huge funding, Ly said, citing as an example the efforts made to clean the 8km long Nhieu Loc Canal in HCM City.
The restoration work, ongoing since 2008, has taken many years and US$685 million thus far.
Nguyen Van Thuy, Director of the Centre for Environment Monitoring, said Vietnam has about 3,450 rivers and springs with length of at least ten kilometers each, their total surface water is about 830 billion cubic metres.
The major rivers in the three regions are: Hong (Red) River, Thai Binh River, Bang Giang River, Ky Cung River, Ma River, and Ca River in the north; Vu Gia River, Thu Bon River and Ba River in the centre; and Dong Nai River and Mekong River in the south.
The water volumes in these rivers were showing vast differences during different seasons, and the quality of the water had also degraded, and the risks of water exhaustion were alarmingly visible, Thuy said.
He said that in the Red River Delta, 80% of water used for daily activities became wastewater, making the region the largest wastewater discharger in the country.
The wastewater contained many pollutants including those generated by industrial production in trade villages, industrial zones, hospitals and farms, Thuy said, emphasising that water pollution was a major challenge for the region and the country.
According to the Construction Ministry, Vietnam has 37 wastewater treatment plants in urban areas with capacity of 890,000 cubic metres daily, dealing with just 12-13% of discharged wastewater.
Nguyen Hong Quan from the Institute of Environment and Natural Resources under HCM City National University told the Sai Gon Giai phong (Liberated Saigon) newspaper that demand for water and wastewater treatment increased along with urbanisation.
But the water supply system and wastewater treatment facilities in Vietnam had failed to meet the rising demand, partly because of modest funding, with private investors showing no interest in the sector, Quan said.
The National Environment Report 2016, released in the middle of this year by Ministry of Natural Resources and Environment, says that on average, an urban dweller consumes 105 litres of water daily and in big cities like Hanoi or HCM City, the water consumption per head is about 120-130 litres a day.
About 40% of water consumption in urban areas in Vietnam is from underground sources. HCM City and Hanoi use about 2.63 million cubic metres of water per day, accounting for nearly 26% of the total water consumption in the country.
The report says that improper exploitation and use have decreased both quantity and quality of water in urban areas including HCM City, Hanoi, Vinh Yen city in Vinh Phuc province and Soc Trang city in the province of the same name.
Overexploitation of underground water has also caused water pollution in Hanoi, Phu Ly city in the northern province of Ha Nam, and land depression in HCM City and Ca Mau city.
According to Water Resources Management Department under the Environment Ministry, between 1992 and 2013, average groundwater levels in Hanoi fell by 0.08-0.91 metres every year. This has worsened the degradation of fresh water resources, leading to reduced efficiency in exploitation and increased risks of pollution and land depression.
Urban water supply pipe systems are said to have degraded in all localities, resulting in wastage as well as pollution.
Last year, Hanoi reported a supply of 880,000- 900,000 cubic metres of water every day, but lost 23% because of degraded water pipelines. In 2014-2016, the water supply pipeline from Da River to the city broke 16 times.
Severe water pollution has been detected in urban areas with excessive concentration of ammoniac as well as heavy metals like lead, arsenic and manganese.
In Hanoi, water in Hoang Mai and Long Bien districts has been contaminated by arsenic for years. High concentrations of iron were found in the districts of Hai Ba Trung, Ba Dinh, Ha Dong, Thanh Xuan, Tay Ho, Hoang Mai, Bac Tu Liem and Nam Tu Liem.
The concentration of ammoniac was found to be dozens of times higher than permitted levels in almost all 34 wells located near 13 water treatment and supply stations in the city.
Residents are very worried about the health implications of such reports.
For examples, arsenic is a chemical element found in nature and some manmade products like pesticides. Consumption of 0.3-30mg of arsenic can cause acute poisoning within 30-60 minutes. Long-term exposure to the element can damage the nervous, cardiovascular and digestive systems and increase the risk of cancer.
High concentration of iron and/or ammoniac can change taste, colour and characteristics of food, making them less digestive or more prone to triggering diseases.
Ly from the Centre for Community and Environment Research said that Vietnam had relatively proper legal framework to manage its water resources, but enforcement has been weak.
He said stronger law enforcement and improved legal frameworks were needed to protect fresh water resources and control water pollution.
Other experts have called for a comprehensive, thorough plan to dredge and clean polluted rivers and canals, improve wastewater treatment works, upgrade urban sewage systems and drastically limit the exploitation and use of underground water.