Up to 80 percent of the sicknesses suffered by people nationwide are caused by polluted water, a senior official has said.
These sicknesses have also caused the death of many children, he added.
Hoang Van Bay, deputy head of the Water Resource Management Department at the Ministry of Natural Resources and Environment, said most of the patients came from poor localities.
Diseases related to unclean water use have become a major problem in the country, he stressed.
People in several localities have reported being infected with "strange" diseases in large numbers and the main cause is polluted water sources, Bay said at a ceremony on Tuesday in Hanoi to commemorate the World Water Day (March 22) and 60th anniversary of the World Meteorological Organization.
A recent study found water supply in 1,000 communes nationwide was seriously threatened by pollution, mostly in the northern delta and the Mekong Delta. Arsenic contamination in water sources was a threat for the nation's population.
According to the Water Resource Management Department, wastewater from industrial production and urban areas were the main cause of water pollution.
The issue was reinforced by the Health Ministry at a conference held in Ho Chi Minh City on March 23 to review a project to improve community health through personal and environmental hygiene.
Nguyen Huy Nga, head of the ministry's Preventive Health Department, said they have identified the ten most frequent infectious diseases in 2009 and found there has been an increase in number of patients suffering from waterborne diseases.
In a recent water pollution case, thousands of fish were found dead in Hanoi's Truc Bach Lake over the past week. Most of the dead fish are small chubs, according to people living around the famous lake in Ba Dinh District.
Vu Thi Ly, director of the Truc Bach Joint Stock Company, said Truc Bach Lake was the gathering place of wastewater from three downtown districts and that the main cause for the pollution caused by inorganic substances and bad weather.
According to a United Nation report released March 22, transforming wastewater from a major health and environmental hazard into a clean, safe and economically-attractive resource is emerging as a key challenge in the 21 st century.
The report "Sick Water? The central role of wastewater management in sustainable development" says some two million tons of waste is being discharged daily into rivers and seas, spreading disease to humans and damaging key ecosystems such as coral reefs and fisheries.
The sheer scale of dirty water means more people now die from contaminated and polluted water than from all forms of violence including wars.