Imbe Water Purification Plant No. 6 Filtration Pond

At the End of the Row

Imbe Water Purification Plant No. 6 Filtration Pond (忌部浄水場六号濾過池) is a concrete slow sand filter bed dating from 1919 at the Imbe water treatment plant in Higashi-Imbe-cho, Matsue City, Shimane Prefecture, and registered as a Registered Tangible Cultural Property of Japan on 18 April 2008. It closes the eastern end of the row of six beds and matches Nos. 3, 4 and 5 in size and form, with an area of 692 square metres.

At the centre of its north side is a regulating well, circular in plan with a radius of 1.2 metres. The housing over that well is where this bed shows its character.

A Housing Dressed in Geometry

The Agency for Cultural Affairs describes the well housing of the Imbe Water Purification Plant No. 6 Filtration Pond as geometric in design. It is finished in mortar, with a half-cylindrical base, and the cornice under the eaves carries a continuous band of flattened hexagons.

Take a hexagon, squash it sideways, and repeat it without a break. That is a very different idea from the housing on bed No. 2, which simplifies the capitals and bases of classical architecture. Here the ornament owes nothing to architectural parts; it is pure pattern.

Each of six identical utility huts was given its own design. The Japan Society of Civil Engineers, writing about the neighbouring Senbon dam, singled out the six well housings, along with the collecting well, as structures with real value as part of the landscape. The registration criterion is contribution to the historic landscape of the country.

What to Notice

When you look at the Imbe Water Purification Plant No. 6 Filtration Pond housing, start by raising your eyes to the eaves. Up close you see each flattened hexagon; step back and the band becomes a single rhythm.

Then look down at the base. Its half-cylinder reads as the round well rising out of the ground, in contrast with the straight cornice above. Round base against angular pattern is what makes this small structure work.

The well here has a radius of 1.2 metres, noticeably smaller than the 1.8 metres recorded for bed No. 2, and the housings differ in bulk accordingly.

Visiting

The Imbe Water Purification Plant No. 6 Filtration Pond is inside an operating treatment plant and is not open to the public. Visits depend on whether the Matsue City Water and Sewerage Bureau is accepting them, so check in advance.

On a visit, walk the row from west to east and finish at bed No. 6, which lets you compare the six housings in order. Follow staff instructions on photography.