Assets

Impounding Reservoirs

The Water Authority operates ten upland impounding reservoirs, ranging in capacity from under 1 million gallons to over 1,000 million gallons. The largest of these, Sulby Reservoir, was completed in 1982. Its construction secured the availability of adequate raw water for treatment and distribution to meet the Island’s needs well into the 21st century. However, it should also be noted, that over two thirds of the water presently supplied to the Authority’s customers is still abstracted from the four oldest reservoirs, built between 1875 and 1905.

Water Treatment Works

The Water Authority operates two water treatment works, one in Douglas and the other in Sulby.

The one in Sulby, opened in October 2005, whilst the other in Douglas came into service in February 2008. These new works incorporate the latest multi-stage treatment processes utilising dissolved air flotation and manganese removal technologies.

Distribution System

The Water Authority, on its formation in 1972 from several smaller predecessor organisations, inherited a complex system of mains service reservoirs and pumping stations, much of which had developed as independent units according to the Water Board promoting each scheme. Many of the old cast iron mains date back to the mid nineteenth century and many of the service reservoirs and pumping stations from the 1940’s and 50’s.

Since 1972, the Authority has continued to develop the system to meet ever increasing demands for water from an expanding population. There are now over 66 kilometres of large diameter raw water mains and over 1,400 kilometres of treated water mains. There are 33 underground treated water service reservoirs, ranging from small covered tanks storing only 5,000 gallons up to large concrete structures holding 5 million gallons.

While much of the water supplied by the Authority flows under gravity all the way from the impounding reservoirs through the treatment works and into the service reservoirs, in many of the higher areas water must be pumped up into supply. Three of the treatment works incorporate pumping stations, and in addition there are 13 other pumping stations within the distribution system.

Supply Map

The supply map is being redesigned and will be available soon.

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