The arsenic level in one sample was twice than the permitted level.

At a meeting with the Hanoi People's Committee on Tuesday, Deputy Minister of Health Nguyen Thanh Long asked Hanoi authorities to close the My Dinh Water Supply Station of the State-owned Hanoi Water Supply Company until the station could ensure that the concentration of arsenic is at a safe level.

According to scientists, arsenic is four times more toxic than mercury and has an adverse impact on the circulatory and nervous system.

Depending on the individual, symptoms can vary, such as hair loss, nausea, weight loss, cancer and memory loss.

The Ministry of Health has also asked all water plants in the city to perform periodic tests and strengthen management of water quality to meet national standards on tap water.

In a recent inspection of water quality at the Nam Do new residential area in Hanoi, the Ministry of Health’s inspectors also found that tap water contained a high concentration of chlorine and permanganate.

Water samples collected from tanks of some households failed to meet the standards on nitrite, permanganate and chlorine. In the roof tanks, there were microorganisms (coliform) at low levels.

From June 27 to 30, the Ministry of Health checked water quality at 16 water plants and eight water supply stations and some  households in Hanoi.

The water samples taken from 16 water plants and eight water supply stations did not meet five out of 107 criteria.

Specifically, the My Dinh water supply station is the only one that has high arsenic concentration.

All 20 water samples collected from water supply facilities have a high chlorine concentration while 150 out of 155 samples taken from households have a chlorine concentration lower than the permitted level.

For ammonium concentration, seven out of 20 samples from water supply facilities and 15 out of 155 samples from households did not meet the permitted level. For permanganate, it was 12 out of 20 and 40 out of 155, respectively.