Hirase Water Purification Plant Former Intake Gate

Where the Intake Conduit Came Up for Air

The Hirase Water Purification Plant Former Intake Gate (平瀬浄水場旧取水口門部) is a stone conduit portal 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 September 2, 1998. It marks the point where the conduit bringing raw water from the Arakawa River emerged inside the plant.

Water left the river intake, ran through a tunnel and poured into the plant through this gate. The tunnel's entrance survives as the registered No. 2 Tunnel Upper Portal, so the two gates bracket a single conduit. The route has since been abandoned, and the gate now stands dry within the grounds.

It is big: 14.4 metres wide and 11.0 metres high. The portal at the tunnel entrance measures 4.3 metres wide and 3.3 metres high, and neither mouth of the Katayama delivery tunnel comes close either. The Agency for Cultural Affairs counts it as one building and classes it as a stone conduit portal.

Why It Was Registered

Of the six Hirase waterworks structures on the register, the Hirase Water Purification Plant Former Intake Gate is the only one listed as a structure that has become a model of design. The other five were registered for their contribution to the historic landscape.

The Agency calls the gate a symbol of the modernisation of the water supply and a fine example of the plant's stonework. That it earned the design criterion after losing its function is the point: the assessors were judging the portal as masonry, not as plumbing.

It was registered on September 2, 1998, the same day as the Former Katayama Tunnel Lower Portal on the delivery side. The gate that let water in and a gate that sent it out joined the register together.

The Inscription Over the Opening

A four-character tablet sits above the opening. The waterworks bureau transcribes it as 決渠為雨 and the Agency for Cultural Affairs as 沢渠為雨, so the first character differs between the two sources. If you get the chance, check which one is actually carved.

If the reading is 決渠為雨, it is the second half of a couplet from an irrigation song in the Han-dynasty history Hanshu: open the channel and it becomes rain, watering the fields. The No. 2 Tunnel portal at the intake end carries a tablet that echoes the first half, about raising the spade to make cloud. The couplet seems to have been split between the two ends of the conduit, with the rain line placed where river water finally reached the town's plant.

Standing in front of the gate, notice the contrast between the masonry, which rises 11.0 metres, and the opening at its centre. Building something this substantial for what was essentially a water outlet tells you how much civic pride Kofu invested in its new waterworks.

Visiting

The Hirase Water Purification Plant Former Intake Gate stands inside the working Hirase plant and cannot be visited freely. The only way in is a group tour arranged through the Kofu City Waterworks and Sewerage Bureau.

The bureau's tour map traces the treatment process and does not say whether this gate can be seen from the route. When booking, mention that you would like to see the Former Intake Gate and ask whether it can be included. Photography is not covered in the published guidance, so ask about that at the same time.