Handayama Water Distribution Area No. 2 Reservoir

Handayama No. 2 Reservoir: A Meiji-Era Waterworks Marvel

Tucked into the green hillside of Handayama Botanical Garden in Okayama City, the Handayama No. 2 Reservoir (半田山配水地二号配水池) stands as a remarkable testament to early modern Japanese engineering. Built in 1905 (Meiji 38), this circular brick-and-concrete reservoir has been quietly supplying clean water to the citizens of Okayama for over 120 years — and it is still in active operation today. Registered as a national Tangible Cultural Property in 2005, the reservoir offers visitors a rare glimpse into the origins of Japan's modern waterworks infrastructure, set against the backdrop of one of Okayama's most beloved botanical gardens.

The Birth of Okayama's Modern Water Supply

In the late 19th century, outbreaks of cholera and dysentery prompted cities across Japan to urgently develop modern water supply systems. Okayama was no exception. In 1897 (Meiji 30), the city invited the distinguished civil engineer Chōsaku Yoshimura — who had previously worked on the waterworks of Nagasaki, Osaka, and Kobe — to survey and design a new water system for the city. Under his plan, water would be drawn from the Asahi River at the Mino Water Purification Plant, filtered through slow sand filtration beds, and then pumped up to reservoirs on the slopes of Mount Handayama. From there, the water would flow by gravity to households throughout the city.

Construction began in 1903 (Meiji 36) and was completed in 1905 despite difficulties caused by the Russo-Japanese War. On July 23, 1905, a grand opening ceremony was held at the Handayama reservoir site, marking Okayama as the eighth city in Japan to establish a modern waterworks system — following Yokohama, Hakodate, Nagasaki, Osaka, Tokyo, Hiroshima, and Kobe. For a regional city of its size, this was a remarkable achievement.

Architecture and Engineering of the No. 2 Reservoir

The No. 2 Reservoir sits immediately west of the No. 1 Reservoir and shares the same structural design. It is a circular underground reservoir with a diameter of 20.65 meters, a depth of 4.5 meters, and a capacity of 1,170 cubic meters. The underground perimeter walls are constructed of brick-lined concrete, while above ground, the exterior walls feature ventilation openings and a ventilation tower at the central apex of the domed roof.

Inside, concentric double partition walls divide the space into ring-shaped chambers, with brick arches spanning the tops of these walls. The roof is a reinforced concrete truncated spherical vault. This ingenious design ensured even water distribution and adequate ventilation while maintaining structural integrity. The use of red brick combined with locally quarried granite — a hallmark of Okayama's Meiji-era infrastructure — creates a distinctive aesthetic of red and white contrast that characterizes all the waterworks facilities in the Handayama complex.

The construction was overseen by engineers Chōsaku Yoshimura and Tōjirō Sano, and was funded through national treasury subsidies and prefectural grants. The fact that three such circular reservoirs — No. 1 and No. 2 from 1905 and No. 3 from 1919 — survive in excellent condition and remain operational is nationally significant, as circular reservoirs of this type are extremely rare throughout Japan.

Why It Was Designated a Cultural Property

In February 2005, exactly 100 years after Okayama's waterworks began operation, ten water supply-related facilities were registered as national Tangible Cultural Properties. The Handayama No. 2 Reservoir was among them. The designation recognized several factors of cultural and historical importance:

• It is one of the few surviving circular reservoirs in Japan, representing a rare structural type in the history of waterworks engineering.
• It forms part of a remarkably complete set of Meiji-era water supply facilities — from intake to filtration to distribution — that remain in working condition.
• The construction demonstrates the sophisticated blending of Western engineering techniques with local materials, particularly the distinctive brick-and-granite aesthetic.
• Together with the other registered facilities, it documents the technological evolution of Japan's modern water infrastructure from its earliest period.

The Handayama distribution complex is also notable as one of the few waterworks facilities in Japan that is open to the public, making it a valuable educational and cultural resource.

Highlights and Things to See

A visit to the Handayama No. 2 Reservoir is best experienced as part of a broader exploration of Handayama Botanical Garden, where the reservoir and its companion structures are located. Here are the main highlights:

• The Circular Reservoirs: The three domed reservoirs, partially buried in the hillside, are a striking sight. Their brick ventilation towers and the distinctive Okayama city emblem on the ironwork of the ventilation openings are charming details to look for.
• The Hexagonal Metering Rooms: Near the reservoirs, two hexagonal brick metering rooms (量水室) — one from 1905 and one from a later expansion — display elegant brickwork craftsmanship.
• The Former Office Building: A wooden single-story Meiji-era building with hipped roof and Western-style windows, now used as storage but still retaining its historic character.
• Handayama Botanical Garden: The 110,000-square-meter garden surrounding the reservoirs features approximately 3,200 species and 150,000 plants. Cherry blossoms in spring (around 1,000 trees), hydrangeas in early summer, and autumn foliage make every season rewarding.
• Ipponmatsu Ancient Tomb: Near the hilltop, this keyhole-shaped burial mound (前方後円墳) adds an archaeological dimension to the visit.
• Panoramic City Views: From the garden's higher elevations, visitors enjoy sweeping views of Okayama's cityscape.

Nearby Attractions

The Handayama area is conveniently located near several other points of interest in Okayama:

• Okayama Waterworks Memorial Museum (岡山市水道記念館): Housed in the original Meiji-era power house and pump room of the Mino Water Purification Plant (also a registered cultural property), this interactive museum tells the story of Okayama's water supply. It reopened in 2022 with hands-on exhibits. Free admission; closed Mondays.
• Okayama Korakuen Garden (岡山後楽園): One of Japan's three most celebrated landscape gardens, located about 3 km south of Handayama. A must-visit destination.
• Okayama Castle (岡山城): The striking black-walled "Crow Castle" stands adjacent to Korakuen Garden, offering historical exhibits and panoramic views from the tower.
• Kibiji Cycling Route: For a full-day cultural excursion, the scenic cycling path through the historic Kibi region connects ancient shrines, burial mounds, and rural landscapes southwest of the city.