The Vinaconex Water Supply Joint Stock Company dumped untreated wastewater into the Dong Bai stream in Thach That District.

It had used the water to clean pipe systems and reservoirs as ordered by the Hanoi People's Committee on October 18. The reservoirs, with a capacity of 30,000 cubic meters of water each, were cleaned manually by workers without using any chemicals, according to Hanoi's Department of Natural Resources and Environment.

However, in a document sent to the Hanoi People's Committee recently, the department also said that the water was then directly dumped, untreated, into the Dong Bai stream.

About 2,500-3,000 cubic meters of water were dumped into the environment, the department said, adding that Viwasupco warned neither locals nor authorities about the dumping.

The Hanoi People's Committee has ordered Viwasupco to strictly manage and operate its reservoirs properly to keep the environment clean. It also ordered the firm to find a different way to dispose of the water.

If the quality of the dumped water fails to meet standards, Viwasupco would be fined in accordance with current laws, the committee added. There was no information, however, on whether the company's latest action would be punished.

The contamination scandal broke out on October 10, two days after a 2.5 ton tanker was seen dumping used oil into a creek in Hoa Binh Province that feeds into the Da River, Viwasupco's water source.

That day, residents in the southwest of Hanoi 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 with, only for other purposes like washing clothes and bathing. Worried residents had to resort to using bottled water, which saw sales and prices soar. People also carried cans and bottles and waited in line for hours to get clean water from tankers sent by the city administration.

On October 17, Viwasupco restored its water supply after suspending it for one day for cleaning its pipes and reservoirs. On October 22, the city announced the water was safe enough for drinking and cooking with.

The company had called itself the biggest victim in the scandal, before offering apology on October 25. Yet it has not announced any kinds of compensation to around one million Hanoi residents affected by the contamination.

Police in Hoa Binh Province, where the contaminated creek and Da River section flows through, have arrested three suspects for dumping the used oil. They are continuing investigations into the responsibilities of all possible parties involved in the incident.