Water Supply Day

What Is Waterworks Day?

October 17 is Waterworks Day in Japan. On October 17, 1887, Yokohama in Kanagawa Prefecture began supplying water through Japan's first modern waterworks. Earlier water systems simply carried river water through wooden pipes, and the water quality easily deteriorated. Yokohama's modern system filtered water taken from a river and sent it under pressure through iron pipes to neighborhoods, marking the starting point of Japan's water supply system.

Why Modern Waterworks Began in Yokohama

After its port opened, Yokohama's population grew rapidly, but much of the city was built on reclaimed land, and wells produced only salty water.

• Water shortages and disease: Good water was hard to find, and cholera broke out repeatedly during the Meiji era. Securing safe water was an urgent issue for the city.
• Designed by British engineer Palmer: Yokohama's waterworks were built under the guidance of Henry Spencer Palmer, a British Army engineer. Water was taken near the confluence of the Sagami and Doshi rivers and carried about 44 km to the Noge-yama water purification plant.
• Spreading nationwide: After Yokohama, modern waterworks were built in Hakodate, Nagasaki, Osaka, Tokyo, and elsewhere, and waterborne diseases fell sharply.

Trivia About Japan's Water Supply

The tap water we use every day has some little-known stories.

• About 98% coverage: Today, about 98% of Japan's population is served by public water supply.
• Few countries have drinkable tap water: Only a limited number of countries have tap water that is safe to drink straight from the tap, and Japan is considered one of them.
• Water Supply Week in June: Every year from June 1 to 7 is Water Supply Week, when purification plants across Japan hold public tours.

More Waterworks Trivia

• Edo's water system: In the Edo period, the city of Edo had the Kanda and Tamagawa aqueducts, which distributed water through wooden and stone pipes. It is said to have been one of the largest systems in the world at the time.
• Advanced treatment: Some purification plants use ozone and activated carbon in addition to standard filtration to remove musty odors.
• Mostly soft water: Most of Japan's tap water is soft water, low in calcium and magnesium, which is said to make it good for bringing out the umami of dashi broth.
• Aging pipes: Many water pipes installed during the rapid-growth era are due for replacement, and upgrades and earthquake-proofing are underway across the country.
• Traces at Nogeyama: The site of the Nogeyama purification plant, the hub of Yokohama's first modern waterworks, is now part of Nogeyama Park.

Ideas for Waterworks Day

• Make a point of drinking water regularly. Carrying tap water in a reusable bottle also cuts down on plastic bottle waste.
• Check where the emergency water distribution points are in your area using a hazard map or your city's website.
• Check your emergency water supply at home (about 3 liters per person per day is a common guideline).
• Look for tours of a nearby purification plant or waterworks museum.

A Day to Appreciate Every Glass of Water

Waterworks Day on October 17 is a day to notice a convenience we rarely think about: safe water whenever we turn on the tap. The modern waterworks that began in Meiji-era Yokohama protected people from disease and supported the growth of cities. Today, as you drink a glass of water, take a moment to think about the long journey it made to reach you.