Sue Water Purification Plant

Kanazawa's First Waterworks

The Sue Water Purification Plant (末浄水場, Sue Jōsuijō) is a municipal waterworks in Suemachi, Kanazawa City, Ishikawa Prefecture, which began supplying water in 1930 as the city's first modern treatment plant; twelve of its original slow-filtration structures are listed as National Registered Tangible Cultural Property. It lies about 8 kilometres south-east of central Kanazawa, on the middle reaches of the Sai River.

The water comes from the Terazu Canal, an irrigation channel dug in 1665 to open new rice land. An intake well on the canal's middle course feeds a buried main about 1.8 kilometres long that runs to the plant. An Edo-period farm ditch, in other words, became the headwater of a 20th-century city supply.

Two engineers shaped the project. Ōi Seiichi, a professor at Kyoto Imperial University, supervised the overall plan, and in 1923 the city hired Ishii Kazuo, formerly a waterworks engineer in Nagoya, to lead the survey. From 1928 Ishii ran the Kanazawa waterworks office as chief engineer and prepared the working design. Along the way the original scheme submitted to the national government in June 1927 was heavily revised, and a landscaped garden was written into it. The Agency for Cultural Affairs takes that revision as a sign of Ishii's hand.

When the Saigawa Dam was completed in 1965, a rapid-filtration line was added on the same site. Together the two systems now treat 105,000 cubic metres a day. All twelve registered structures belong to the older slow-filtration line, and they are still in service.

A Plan Drawn by the Path of the Water

What sets the Sue Water Purification Plant apart is its layout. The supply main runs directly beneath the road leading to the main gate and splits in two just inside it. One branch passes through a receiving well, where flow and quality are adjusted, and on into three sedimentation basins at the south-east corner of the site. The other feeds the fountain in an ornamental pool north of the gate.

Kanazawa City describes two axes. The water-intake axis runs north from the gate through the pool; the supply axis crosses it at a right angle and runs straight west along a service walkway to the Slow Filtration Treated Water Collecting Well at the far edge of the site. Six slow sand filters line that walkway, three on each side, each paired with a clear-water well and a small well house placed in mirror image across the path. Where the two axes meet stands the pavilion of the front garden. From the sedimentation basins the water passes beneath that pavilion, through the filters and into the collecting well, moving by gravity alone and growing cleaner as it goes.

The front garden itself was finished in 1932, two years after the plant opened. The pool is formed from three overlapping oval concrete basins set at different levels, so that water stepping down through them could be watched for quality. Photographs taken at completion show the fountain throwing an arc of water onto the funnel-shaped crown of the pavilion roof; today the pressure is kept low and the spray stays inside the pool. Stone walls and clipped hedges are arranged symmetrically between pool and pavilion, and the whole garden is composed of straight lines, circles and ellipses.

That design earned the grounds national designation as a Place of Scenic Beauty on 22 February 2010, under the name Sue Water Purification Plant Garden (末浄水場園地). The designated area of 80,103.18 square metres covers almost the whole site, and all twelve registered structures stand inside it. Earlier, in 1985, the Ministry of Health and Welfare had included the plant in its selection of 100 notable modern waterworks for its setting and landscape.

The Twelve Registered Structures

Registration came in two stages. On 28 August 2001, eleven structures were entered: three slow-filtration sedimentation basins, six slow sand filters, the collecting well and the treated-water pump room (registration numbers 17-0043 to 17-0053). On 29 November 2016 the Former Receiving Well House beside the main gate followed (17-0260). A metering house at the Ōkuwa distribution reservoir, outside the plant, was registered the same day.

Different criteria apply. The collecting well and the receiving well house were registered for serving as models of design; the nine basins and filters and the pump room were registered for their contribution to the historic landscape. The first two are buildings meant to be looked at; the rest are civil works and small service buildings that matter chiefly as an ensemble.

Following the water is the easiest way to keep them straight. Inside the main gate, on the right, the Former Receiving Well House faces west. Behind it the three sedimentation basins run from No. 1 in the south to No. 3 in the north. West of the front garden lies the filter field: Nos. 1, 3 and 5 on the south side of the walkway and Nos. 2, 4 and 6 on the north, numbered from east to west. At the western end of the walkway stands the collecting well, with the pump room just to its north. The filters sit on lower ground than the sedimentation basins, and it is that drop that carries the water west.

Visiting and Getting There

The front garden is open to anyone without a booking, from 9:00 a.m. to 4:00 p.m. (4:00 p.m. is the time visitors must leave), free of charge. It closes from 29 December to 3 January and on Saturdays, Sundays and public holidays in January and February. Eating and smoking are not permitted, and visitors are asked not to bring pets.

The basins, filters and other water-treatment facilities can be seen only on guided tours booked in advance. Tours are aimed at groups such as local governments and community associations, and applications go through Kanazawa City's online application service at least two weeks ahead. They run on weekdays from 9:30 a.m. to 12:00 p.m. and from 1:30 p.m. to 3:30 p.m., last about 40 minutes, and cover the treatment process and the sedimentation basins and filters. Schools should contact the Waterworks Division of the Kanazawa City Public Enterprise Bureau directly (076-229-2006, weekdays 9:00 a.m. to 5:15 p.m.). Individual visitors have had a chance to go further in during an annual open day, the Kanazawa Water Festa, held around Water Week in early June; check the bureau's announcements each year.

The bureau's visitor information says nothing about photography. This is a working treatment plant, so on a booked tour it is best to ask the guide before taking pictures.

By public transport, take a Hokuriku Railroad bus bound for Tobu Shako from JR Kanazawa Station, ride to the terminus at Tobu Shako, and walk about 8 minutes. The address is 1-1 Suemachi, Kanazawa City.