June 24, 2025
TOKYO – An increasing number of municipalities are preparing simple shower systems that use purified rainwater collected in swimming pools or other places, in anticipation of water outages during disasters.
These showers, which provide hot water, are expected to help reduce evacuees’ physical and mental stress, which raises hopes that they will contribute to preventing disaster-related deaths.
The Cabinet Office’s guidelines on the importance of bathing and showering at evacuation centers say: “[Showers] make one’s body clean and will also prove effective in relieving stress” and “it is necessary to cleanse the body to prevent infectious diseases.”
However, it is estimated that more than 50 liters of water are required for an adult to take a shower. In light of this, several private companies have been developing water treatment devices tailored to simple showers in recent years.
The basic mechanism is the same. After an alternative water source such as a swimming pool, a river or well water is secured, the water is pumped up to remove impurities through the use of dirt-absorbent powder or activated carbon filters. Then chemicals such as chlorine are added to disinfect the water, and the water is heated with a boiler.
The simple showers have the advantage of being portable. They can be mounted on a vehicle and transported, with a private shower room able to be set up immediately when used with a tent, for instance. It costs about ¥5 million to set up a single unit.
There is also a circular-type simple shower unit that can clean the water after it is used for washing the body, by recycling it back into the unit. The device developed by WOTA Corp., a startup launched by a group of University of Tokyo graduates, can reutilize more than 98% of the water.
“With 100 liters of water, the taking of 100 showers can be made possible, which provides people with a shower even in places where water is scarce,” a spokesperson for the company said.
Simple showers installed at evacuation centers gained prominence for the first time in the wake of the 2016 Kumamoto Earthquake. They were also installed in areas hit by torrential rains in western Japan and the Hokkaido Eastern Iburi Earthquake, both in 2018, making their usefulness widely known.
For the 2024 Noto Peninsula Earthquake, after which it took about five months for the problem of water outages to be solved, simple showers were delivered from across the country to affected areas. In late January 2024, Keisuke Nakane, a technical advisor of Kuritac Co., a Tokyo-based subsidiary of Kurita Water Industries Ltd. — a manufacturer of water treatment systems — provided the company’s products to a municipal elementary school that was being used as a temporary evacuation center in Nanao, Ishikawa Prefecture.
A total of 3,800 people were said to have used the hot showers at the center over a period of about two months during the winter.
“There were those who couldn’t take a bath for a week, and I strongly felt the need for providing simple showers,” said Nakane. The company’s device was also used as a washing machine at the evacuation center.
In late March, a working group of the government’s Central Disaster Management Council presented new damage estimates in the event of a Nankai Trough earthquake. Up to 36.9 million people in 40 prefectures, including Tokyo, were predicted to be affected by water outages on the day after the quake.
For the water outages to be mostly solved, it would take eight weeks in the Tokai and Shikoku regions and four weeks in the Kinki region, the council stated. The amount of water needed for drinking and cooking for three days is estimated to be 9 liters per person, which the government recommends households to stockpile.
It’s difficult and expensive to secure large amounts of water for daily use such as taking a shower, using a toilet and washing clothes. But the number of municipalities and companies purchasing simple showers as a necessary measure in times of disaster is increasing.
In February, the municipal government of Nankoku, Kochi Prefecture, a city expected to be hit by a tsunami with waves as high as 15 meters in the event of a Nankai Trough earthquake, bought four simple shower systems developed by a company based in Kochi City. The municipal government plans to use them at four junior high schools in the city, which are to function as evacuation centers.
“Whether or not a shower is available at an evacuation center greatly affects the quality of daily life for evacuees,” said a head of the crisis management section of the city government.
“We decided it would be indispensable to have them to prevent deaths indirectly related to a disaster.”