Handayama Water Distribution Area Additional Water Metering

Handayama Water Distribution Reservoir Additional Metering Room: A Gem of Early Showa Waterworks Architecture

Nestled on the hillside of Handayama in Okayama City, the Additional Metering Room (Zōsetsu Ryōsui-shitsu) of the Handayama Water Distribution Reservoir stands as an elegant testament to Japan's early modern waterworks heritage. Built in 1939, this compact hexagonal structure may be small in stature, but it carries tremendous significance as a registered tangible cultural property that illustrates the evolution of civil engineering design across the Meiji, Taishō, and Shōwa eras.

A Brief History of Okayama's Pioneering Waterworks

Okayama City's modern waterworks system holds a distinguished place in Japanese infrastructure history. In the late 19th century, repeated cholera outbreaks devastated the city, which relied on river water and wells built atop the alluvial deposits of the Asahi River. In 1897, Mayor Oda Yasumasa commissioned the renowned engineer Yoshimura Chōsaku—who had previously worked on water systems in Nagasaki, Osaka, Hiroshima, and Kobe—to survey and design a modern water supply for Okayama.

Construction began in 1903, and despite disruptions caused by the Russo-Japanese War, the system was completed in 1905. On July 23 of that year, a grand ceremony celebrated the opening of water service at the Handayama distribution reservoir. Okayama thereby became the eighth city in Japan to have a modern waterworks system, a remarkable achievement for a regional city at that time.

The Metering Rooms: From Meiji Elegance to Shōwa Practicality

The Handayama site features two metering rooms that chronicle the stylistic evolution of waterworks architecture in Japan. The original metering room, built in 1905 during the founding of the waterworks, is a hexagonal brick structure situated at approximately 35 meters elevation on Handayama. It showcases refined Western-influenced detailing, including a triangular pediment with a keystone motif above its entrance, classical order elements, and round windows framed in granite—a reflection of the Meiji era's enthusiasm for Western architectural styles.

The Additional Metering Room, constructed in 1939 during the third expansion of the water system, stands adjacent to the west of the original. While it faithfully follows the hexagonal plan and basic design language of its predecessor, its execution is somewhat simplified, reflecting the pragmatic spirit of the early Shōwa period. The walls are clad in tiles arranged to resemble stretcher-bond brickwork, while the window frames and pilaster elements are finished in washed mortar. This graceful balance of continuity and adaptation makes the Additional Metering Room a fascinating study in architectural dialogue across three decades.

Why It Is Designated as a Registered Tangible Cultural Property

The Additional Metering Room was registered as a national tangible cultural property on February 9, 2005, along with the other principal structures of the Handayama Water Distribution site. Its registration recognizes several key values. First, the structure demonstrates a thoughtful approach to design continuity, faithfully echoing the original metering room's hexagonal form and ornamental vocabulary while adapting to the materials and methods of its own era. Second, as part of a larger ensemble of waterworks buildings spanning from 1905 to the early Shōwa era, it contributes to a rare and coherent grouping of historic water infrastructure that illustrates the technological and aesthetic development of Japanese civil engineering. Third, it stands as a representative example of early Shōwa-period reinforced concrete construction applied to public utility architecture, a building type that is increasingly at risk of being lost.

Highlights and What to See

The Additional Metering Room rewards close inspection. Its hexagonal plan is immediately striking—a geometric form rarely encountered in utilitarian architecture. The tile-clad exterior, designed to mimic traditional brickwork, demonstrates the ingenuity of early Shōwa builders in using modern materials to maintain visual harmony with older neighboring structures.

Visitors should take time to appreciate the surrounding Handayama Water Distribution complex as a whole. The three circular reservoirs (Numbers 1 and 2 from 1905, Number 3 from 1919) are among the rarest examples of their type in Japan, each measuring approximately 21 meters in diameter and still in active use. The original metering room, with its elegant brick construction and granite-framed round windows, provides a beautiful counterpoint to the simplified but no less charming Additional Metering Room. The former office building of the distribution site also survives, completing an exceptionally well-preserved ensemble.

The entire complex is located within the Handayama Botanical Garden, making it possible to combine a cultural heritage visit with a stroll through 110,000 square meters of beautifully landscaped gardens containing approximately 3,200 species and 150,000 individual plants. The hilltop also offers panoramic views of Okayama city and the Kojima Peninsula, and the Ipponmatsu Kofun (an ancient burial mound) near the summit adds yet another layer of historical interest.

Surrounding Area and Nearby Attractions

The Handayama area offers several worthwhile destinations beyond the distribution reservoir and botanical garden. The Mino Water Purification Plant, located to the southeast at the base of Handayama, preserves additional registered cultural properties from the founding era of Okayama's waterworks, including the original slow sand filtration pools, the former power house and pump room (now the Okayama Waterworks Memorial Museum), and a distinctive octagonal brick chimney. The memorial museum, reopened in 2022, offers interactive exhibits about the history and science of water supply.

Okayama's city center lies just a short distance to the south, where visitors can explore the iconic Okayama Korakuen Garden—one of Japan's three finest landscape gardens—and Okayama Castle. The Kibi Plain, to the west, features an excellent cycling route linking ancient shrines and burial mounds from the Kibi Kingdom era.