Hirase Water Purification Plant Former Filter Bed Regulating Well

A Round Well House That Set the Pace of Filtration

The Hirase Water Purification Plant Former Filter Bed Regulating Well (平瀬浄水場旧濾過池整水井) is a reinforced-concrete well house built in 1913 inside the Hirase Water Purification Plant in Hirasecho, Kofu, Yamanashi Prefecture, and was entered on the national register of Registered Tangible Cultural Properties on July 15, 1997. Put up at almost the same moment the plant opened, it housed a control valve that regulated how fast water passed through the filter beds and how much of it flowed.

It is tiny, with a building area of 11 square metres, and round in plan. A frame topped by a pediment, the triangular gable motif of classical architecture, surrounds the doorway, and an inscription sits above it. From 1913 onward the valve inside set the outflow from the filters.

Throttle the flow at a filter's outlet and you change the speed at which water seeps through the sand. That adjustment decides how well the water is cleaned, and Kofu's engineers chose to cover the machinery that made it in a small building with a proper front door rather than a plain box.

Why It Was Registered

The Hirase Water Purification Plant Former Filter Bed Regulating Well was registered on July 15, 1997, the earliest of the six Hirase waterworks properties. Its Yamanashi registration number, 19-0012, places it among the first buildings in the prefecture to join the register after the system was created in 1996. It was listed for its contribution to the historic landscape.

The Agency for Cultural Affairs notes that local people know it as a symbol of Kofu's modernising daily life, and Kofu City's own page on the Suikōan museum also carries a photograph of the well house, captioned as built in 1913.

The filter beds it served have been rebuilt, but the well house that governed them stayed. As a reinforced-concrete structure of 1913, it also marks the opening years of the city's modern water supply.

An Inscription Read From Right to Left

Both the Agency and the waterworks bureau transcribe the inscription above the door as 尽不流々混. Read from right to left, as it was written, it becomes 混々流不尽: the water wells up and flows without end. For the doorway of the well house at the heart of the filters, it is a fitting motto.

A round plan has no corners, so the building shows the same outline from every direction. The pedimented doorframe breaks that symmetry and gives the drum a single front. Even at 11 square metres, the building knows which way it faces.

If you see it, look at three things in turn: the direction of the characters, the little pediment over the door, and the curve of the wall. It is one of the clearest examples at Hirase of function and ornament packed into a very small structure.

Visiting

The Hirase Water Purification Plant Former Filter Bed Regulating Well stands inside the working Hirase plant and cannot be visited freely. Access is limited to group tours arranged through the Kofu City Waterworks and Sewerage Bureau.

The tour map does not mark the well house, so ask when booking whether it can be seen from the route. The valve chamber inside is not open, and the published guidance does not mention photography.