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The Waitakere Filter Station was built in 1927-1928 by an all-Dalmatian work force on Fletcher Construction’s payroll. Excavations were done by hand.
The original compressors used in the filters were made by Sandy Filtration and were still in use in 1991. Auckland City Council employed four men an eight-hour rotating shifts, three on and one off duty. The men and their families lived in council houses a few hundred yards before the Filter Station.
Large drums of lime and sacks of rock alum were hoisted to an upper floor by a gantry and chain pulley. Lime and alum were used to purify the water.
Water came into the filter station from the dam to be treated, and then into eight storage beds with different grades of sand on the bottom. One bed of water was emptied at a time. The washing process began with air forced through the jets, pushing the water through layers of sand. The dirty water was then drained away and the bed refilled; the filtered water went into the clear water tank, originally the break pressure tank.
In the 1940s a large pit was dug, concreted and filled with liquid lime which was pumped into the filters. This lime was brought in by tanker. A computerised switchboard was later installed and all the men needed to do was push buttons to set everything in motion.
In early 1976 a new purifier was built a few metres above the filter station at a cost of $225,000. The purifier, called an accentrifloc clarifier, is 80 feet in diameter with a capacity of five million gallons a day, the first link in the two-stage purification system. Chemicals are added to form a floc to attract discolouration and dirt particles. The water, by then 70 to 80 per cent purified, flows to the filter station for final processing.
The prize for the largest tree in the [add: Swanson] area must go to the giant kauri (Agathis Australis) that grows in the forest to the south of the road to the Watercare Filter Station, just past the car park at the end of Christian Road.
It will be several hundred years old and therefore can claim to be the oldest inhabitant of Swanson.