Water supply was disrupted in areas of Japan’s east coast after the country was hit by an 8.9- magnitude earthquake, its strongest on record.

The Japan Water Works Association is gathering information from prefectures across the country on water supply condition and may release the results through the Ministry of Health, Labour and Welfare within two days, said Takumi Kato, a spokesman at the Tokyo-based association. The number of households affected has yet to be confirmed, he said.

Some residents on northeastern coastal areas of Japan’s main island were evacuated after the coast was hit by a tsunami that engulfed houses, roads and cars. The supply of water is critical in the aftermath of a disaster because of risk of epidemics as displaced people gather in shelters, the World Health Organization said on its website.

"Early in the life of emergency settlements, when displaced people continue to arrive, often in large numbers and in a poor state of health, water supplies may be totally inadequate, and emergency systems need to be set up rapidly to reduce the risk of epidemics," the WHO report said.

Some 30,000 people in the northern city of Sendai and more than 15,000 in Aomori Prefecture were evacuated, according to state broadcaster NHK Television.

Ibaraki, Fukushima

About 20,000 homes in Kita-Ibaraki City, northeast of Tokyo, had no water supply, Hiroshi Numata, a spokesman at the city hall, said in a telephone interview. An unknown number of households in Fukushima Prefecture, north of Ibaraki, had their water supply cut, Akinori Watanabe, a spokesman at the Fukushima Water Supply Authority, said by telephone.

Water supply in some parts of Tokyo, which accounts for 10 percent of Japan’s population, has also stopped, the metropolitan government’s Bureau of Waterworks said in a faxed statement.

Two-thirds of the water supply was cut in Inagi city, west of Tokyo, while service was disrupted in the Tama and Machida areas of western Tokyo because of an electricity outage, the statement said. The bureau couldn’t confirm if the water supply was cut in eastern areas of Tokyo, where it found 45 leaks.