After a million residents of the capital city had to suffer supply of toxic, smelly tap water and spend money on using bottled water instead, the supplier said it was the "biggest victim" in the incident.

At a press conference Thursday, questions were raised about the responsibility of Vinaconex Water Supply Joint Stock Company (Viwasupco), which supplies potable water to 250,000 families in 10 districts in southwestern Hanoi. The company had continued to supply water even after knowing of oil contamination at the source.

Asked if the company has had plans to compensate those affected by the polluted water, its deputy CEO Bui Dang Khoa said: "Viwasupco is the biggest victim in this case and the company hopes the police will soon find true culprit."

He also said that as the case was being investigated, "all decisions related to the interest of Hanoi’s citizens must wait for the investigation's results."

Local officials differed.

Nguyen Khac Long, head of the environment department in Hoa Binh, a neighboring province of the capital city that is home to the water source that Viwasupco takes for processing, said that the department has already collected water and oil samples in affected areas for analysis, and will release the results in a few more days.

Long said the company's fully responsible for checking the water quality and making sure that it is safe before supplying it.

The company had not only continued to supply contaminated water, but it responded to residents' complaints about the smell saying, it could be extra chlorine used to neutralize pollution. An official even said that whether or not the water was smelly was a subjective thing that depended on the individual.

Police in Hoa Binh have launched a criminal investigation into the dumping of used oil upstream the Da River and are looking to press charges of causing environmental pollution against the perpetrator.

On Tuesday last week, a 2.5 ton truck was seen dumping used oil into a mountain creek in Phu Minh Commune. The oil spread contaminated the Tram Stream and then the Dam Bai Lake.

Two days later, Hanoi residents detected an unpleasant, pungent odor in their tap water. Tests of the smelly water by authorities later found that the level of styrene, an organic compound that is probably carcinogenic, was 1.3-3.6 times higher than normal.

Hanoi authorities then warned residents that they should not use the water for drinking or cooking, only for other purposes like washing clothes and bathing. 

Viwasupco currently supplies 300,000 cubic meters of water per day. Around one million people or one eighth of the capital city's residents depend on its supply.

People in Hanoi collect water from a tanker as their tap water has been
contaminated with oil, October 15, 2019. Photo by VnExpress/Ngoc Thanh.

In a statement released Thursday, Hoa Binh authorities suggested that Viwasupco should invest in a closed pipeline system to lead water from the Da River to its tanks.

Viwasupco has been taking water directly to its plant from the Dam Bai Lake in the province’s Ky Son District. Provincial authorities said this was not safe because the lake, a natural one, was way too big, spreading 69 hectares (170 acres) and having a wide basin of 16 square kilometers (6.2 square miles).

Lying near upstream Da River, it receives water from different sources, including streams and mountain creeks, making it difficult to guarantee safety and monitor the water quality.

Like other water treatment plants in the country, including the biggest one that supplies water to Ho Chi Minh City, a closed pipeline system would take water from the middle level of rivers to avoid trash and in some cases, oil on the surface of the water.

Viwasupco should also have stricter solutions to ensure safety of the source of its water and prepare itself for possible problems in the future by envisaging various scenarios and developing an incident response process.

In case the company fails to ensure the quality of water at the source, it has to stop the entire process and report to the authorities from central to local levels, provincial officials said.

Also Thursday, Hanoi officials said the latest tap water samples have passed safety tests, but continued to advise against drinking or cooking with it.

Nguyen Nhat Cam, director of the Hanoi Center for Disease Control under Hanoi's Department of Health, said all eight tap water samples collected Monday met safety standards for all 107 parametric values including styrene, a carcinogenic that had been found in excessive quantities in supplies to southwestern Hanoi.

"All values are within allowed limits. However the samples were collected three days ago, so we still recommend that people do not use the water supplied by the Da River water plant from Wednesday night for drinking or cooking," he said, adding that the city had instructed the company to resume water supply so people could clean their water tanks.