The reason for a burned and pungent smell detected in the tap water in different parts of Hanoi since last Thursday is a significant amount used oil dumped into an upstream section of the Da River, the biggest branch of the Red River, which flows from Yunnan in Southwest China through northern Vietnam to the Gulf of Tonkin in Vietnam.

A truck with a loading capacity of 2.5 tons was seen dumping the used oil into a mountain creek in Phu Minh Commune, Ky Son District of Hoa Binh Province, a northwestern neighbor of Hanoi, on October 8, the Vietnam Environment Administration under the Ministry of Natural Resources and Environment said Monday.

"After that, there were heavy rains, and the water polluted with oil mixed with waterways that lead to the Da River, and then to areas where the water is taken to supply Hanoi," said Hoang Van Thuc, deputy head of the administration.

The administration also said that Vinaconex Water Supply Joint Stock Company (Viwasupco), which processes water from the Da River and supplies to Hanoi, was aware of the problem even before citizens of Hanoi began to detect the strange smell.

On October 9, the company had hired around 50 people to take the oil out of the canals diverting water into its factory.

A 50-year-old woman, one of the people hired for the job, said the water was heavily polluted.

"The oil was really thick and did not even flow when we poured it through a funnel into barrels and bags. We actually had to use sticks to push the thick oil down because it would get stuck at the mouths of the barrels."

She said the company had cheated the workers by not telling them what the actual job was: "When they hired us for the job, they only told us that we have to remove grass and bush from a stream, but soon we realized that we would have to remove oil, which completely covered the entire stream and had a smell that made me want to throw up."

The administration has demanded Hoa Binh’s authorities and the police to find the truck and the driver that dumped oil into the environment, as well as the company or organization behind the incident.

As for Viwasupco, the administration said the company must take responsibility because it had been aware of the polluted water but still processed it and provided the running water for people in Hanoi.

The company provides 300,000 cubic meters per 24 hours for the entire southwestern part of the capital city, including Thanh Xuan, Hoang Mai, Cau Giay, Ha Dong and several downtown districts.

Since October 10, daily lives of people in those areas have been in disorder because of the unpleasant smell from the water.

Last Saturday, Ha Quoc Tu, a resident in Hoang Mai Distrist, could not continue cleaning vegetables right after he turned on the water.

"A burned smell mingling with another type of smell that feels like the glue used for plastic pipes goes straight into my nose. We don’t know what is wrong with the water but it could not be used," he said.

By Saturday, his family has spent at least VND500,000 (over $20) buying bottled water for cooking.

Hoai Anh, owner of a convenience store in Linh Dam residential area in Hoang Mai, said the demand for bottled water has surged dramatically.

For one Saturday morning, the store sold up to 100 five-liter and 20-liter bottles.

"Sales of bottled water have never been this good. I still owe over 20 orders for the product," she said.

Also on Saturday, Nguyen Thien Thai, another resident in the district, has to bring a 20-liter bottle to buy clean water.

Thai said he had called the bottled water company since the morning but until afternoon, no one had delivered any bottles so he had to take a bottle to buy water at a nearby place.

"We only save the bottled water to bath the kids. The adults still use the tap water for showering and what we got is an unpleasant smell on our bodies hours after that," he said.

Residents at a condo in the district have even contributed money to order a tank truck to carry clean water from other districts to the condo for using.

Residents at a condo in Hoang Mai District gather to get clean water
from a tank truck. Photo by VnExpress/Vo Hai

Many families have brought their clothes to other districts for washing, either at houses of their family members or laundry shops.Parents at Chu Van An Primary School in Hoang Mai have also made the same move so that the school will have access to clean water to cook food for their children.

The story flows in the same direction in Thanh Xuan District.

Dinh Tien Dung at a residential area in Khuong Dinh Ward said Saturday that the "strange odor" has been there in the water for days and show no signs of going away.

The situation has affected his family and 800 others in the area.

Dung said his family had used the smelly water to cook food for two days after the water started having the burned smell, but had to give up and bought bottled water on Saturday morning.

Many locals in Thanh Xuan said they have never experienced tap water with such unpleasant smell before, even when the pipeline is broken.

"But for the past days, the water smells really unpleasant and tastes bitter and pungent. Once it was in my mouth, I had to throw up. It feels like you use an electric bottle to cook water and then the wires get burned," said Nguyen Thi Huan, a local woman.

In April 2009, tap water provided by the company also had a strange smell due to a high amount of chlorine residue.