The O-K Main Kinney Strainer Chamber was installed in 1967 to filter out debri in the main before being sent to Wellington
The O-K Main Kinney Strainer Chamber formed part of the O-K pipeline system, which conveyed raw water from the Orongorongo catchment. Designated as WI-VCH0905TW, the strainer and chamber enhanced the water quality. Its primary purpose was to filter out impurities before the water continued on its journey to Wellington.
Although the Orongorongo–Wellington pipeline was completed in 1926, the strainer itself was introduced in 1969 as part of system improvements. Its function became redundant in 1993 with the commissioning of the Wainuiomata Water Treatment Plant, which assumed responsibility for filtering and treating the water supply.
Water entered through one end of the pipeline, passed through a rotating drum fitted with mesh filter cups, and exited through the opposite end. Any debris trapped in the filters was flushed away via a scour valve that discharged into the lake behind Wainuiomata Lower Dam. An access hatch in the roof likely allowed maintenance crews to remove and clean the filters as needed.
A Kinney Strainer Chamber is a type of filtration structure built into a water pipeline to prevent blockages and protect valves, meters, and other equipment from damage caused by debris carried in the flow. Its primary role was to remove solid material such as sand, rust, or organic matter before the water continued further through the system. The location of the chamber was important because venturi meters for measuring water flow were installed about 100 metres to the west. The chamber itself is made of reinforced concrete.
The term ‘Kinney’ refers to the manufacturer of this particular type of strainer, most likely the Kinney Vacuum Company, later part of Tuthill/Kinney Industries. Renowned for its industrial pumps and fluid-handling equipment, the company also produced large inline and duplex strainers designed for high-pressure water mains, such as the O-K pipeline. These units typically featured removable mesh screens for cleaning and some models had automatic flushing valves that cleared debris without interrupting the water flow.
On display outside the Wainuiomata Water Museum is the strainer which was originally inside this building.
Special thanks to Lance Stewart for some information in this article.
