From Jersey Water website The Jersey New Waterworks Company commissioned the first desalination plant in the British Isles in 1970. The plant was built in an abandoned quarry close to the sea at La Rosière, Corbiere, at the south-west corner of the Island. Sea water was pumped into a deep pond within the old quarry before being abstracted for desalination.
The original desalination plant used a multi-stage flash distillation process, whereby the sea water was boiled under vacuum, evaporated and condensed into a fresh water distillate.
By 1997 the plant had reached the end of its operational life and it was decided to replace this important standby water resource with a modern plant using the Reverse Osmosis process, giving a number of significant operational benefits.
On Friday 9 July 1999, Lieut-Governor General Sir Michael Wilkes officially opened the new plant.
The desalination plant plays a vital role in providing an alternative water source for the Island and when necessary augmenting natural water resources which are predominantly surface derived.
A deep sea water intake shaft and tunnel constructed below the mean low tide level on the foreshore allows sea water to be pumped at all states of the tide, which can vary by as much as 12 metres. A macerator device in the sea water intake shaft chops up seaweed and other large matter. The sea water is stored in the quarry pool, which then allows settlement of any unwanted debris.
The sea water is then transferred from the quarry pool into the primary treatment filters. There are four filters that use a combination of sand and anthracite to filter the sea water, removing suspended solids before micron filtration. On leaving these filters, the sea water is passed through cartridge type filters.
The filtered sea water then passes to the reverse osmosis plant, which consists of four units capable of producing 1,500 cubic metres of fresh water per day.