It is easy to take for granted that the water we use at home and at work will always be pure and will never run out. But in fact tap water is a sophisticated product, requiring a great deal of technology, skill and science and to provide it.

So following on from the last number of weeks exploring the River Lee's industrial and civil engineering heritage is this week's look at the Cork Harbour and City Water Supply Scheme. It is located a half a kilometre up river from the ESB's hydro-electric dam at Inniscarra. At the time of the Scheme's construction, the facility was one of the largest public works undertakings ever built in Ireland. The Government approved IR£40 million in 1973. The total cost in 1982 was IR 48million. The scheme was infrastructural in its nature and was expected to cater for the water supply needs of industry in the Cork area well into 21st century. The Scheme in 2008 serves 110,000 persons in Cork all day every day.

In a wider context, preparations for the water supply scheme coincided with the optimistic economic climate that grew in Ireland during the middle and late 1960s. The country was rapidly emerging from the post-war depression of the late 1940s and 1950s. Emigration was in decline. Staple economic growth was becoming a reality. A regional study of Ireland was commissioned by the United Nations on behalf of the Irish government of the day. It was compiled by Colin Buchanan and Partners and was presented in 1969. The Buchanan Report recommended the establishment of two Government sponsored industrial growth centres located at Cork and Limerick/ Shannon area respectively. The plan did not completely take off but the idea of Cork as a growth centre was pursued somewhat.

The decades of the 1960s and 1970s in County Cork were a time of rapid industrial growth and development in the harbour area. Cork had a considerable variety of industry including Ireland's only steelworks, oil refinery, shipyard and major vehicle assembly plant. In 1969, the first major water using industry, Pfizers was established in Ringaskiddy with a water demand for two million gallons per day. In expectation of further developments and the general policy adopted by the Irish government, building new infrastructure would bring more business. That was acknowledged in the publication of a Cork Harbour Plan in 1972. Cork County Council's development plan of 1967 and the plan to promote the growth of satellite towns led to thinking about the need for an increased water supply.

In the early 1970s Cork County Council and Cork Corporation jointly commissioned a report on the provision of a water supply scheme, which would cater for the future needs in the Harbour and City area. In order to predict future water demand in the Cork area, considerable research was carried out in relation to the growth in demand in Cork City itself. Presented in 1970s, the report formed the basis for the design and construction of the Cork Harbour and City Water Supply Scheme.

Significant impetus was given to the development of the first stage of the Scheme in the early 1970s when the Industrial Development Authority decided to establish two major industrial estates in the harbour area, namely, Little Island and Ringaskiddy. Two sources of underground water were investigated – a carboniferous limestone syncline stretching from Youghal in the east, through Cork City, to Crookstown in the west and the gravel deposits of the Lee Valley west of the City. However, on discovery, the limestone synclines did not have enough bulk quantities of water and the gravel deposits created hard water. From further investigations it was decided to locate the intake site upstream of the present city and draw on the reservoir created by Inniscarra. The Ballincollig Regional Water Supply Scheme was already in place and abstracted water through a pipe built into the wall of Inniscarra dam i.e. upstream of the Dam.

It was decided by Cork County Council, Cork Corporation and the Department of Local Government that Inniscarra Lake, with the assistance of the ESB dam would provide the necessary volume of water needed. Payment would be made to the ESB for the use of the water and compensation given as appropriate for the loss of generating capacity brought about by the water scheme. By 20 September 1973 the Minister for Local Government had approved the contract documents for the waterworks at Inniscarra. The works were completed between the years 1976 and 1982 under the executive authority of Cork County Council.