RESIDENTS of north Wicklow and Dun Laoghaire Rathdown will experience an improvement in the quality of their water supply as a result of major works at the Roundwood reservoir, officially inaugurated yesterday.
But Dublin's chief engineer, Mr Jim Fenwick, admitted that the £5 million improvement scheme will have no effect on the quantity of water produced by the city's oldest reservoir, which has become notorious for running low in periods of drought.
One of the most urgent tasks was to renovate the shafts in its characteristic stone built draw off towers, which were "in danger of collapse", according to Mr Fenwick. If this had happened, it could have "undermined the whole supply system", he said.
The 130 year old reservoir used to provide Dublin with most of its water, until the Ballymore Eustace works were built in the 1940s. Now, it supplies less than a quarter of the capital's expanded population with almost 18 million gallons of drinking water per day.
"Roundwood has always supplied the city with first class water, but it needed upgrading in latter years," Mr Fenwick explained. These works included resanding its filter beds and installing a new chemical building to improve the application of chlorine and fluoride.
The waters of the River Vartry are "slightly acid", because of its course through peaty soils, so lime is now being added to make it neutral. The colour of the water, which had an almost imperceptible brownish tinge, will also improve as a result of this measure.
The Vartry water is filtered through beds of sand, the most traditional method of purification. However, these beds had become degraded and needed to be replaced.
Mr Fenwick said the works completed at Roundwood had brought the plant fully into line with EU regulations on the quality of drinking water, so that the reservoir could continue to make a major contribution to meeting Dublin's water needs into the 21st century.
However, he conceded that Roundwood was "working flat out all the time" because of the huge increase in per capita water consumption in the Greater Dublin area. Since the 1940s, this had gone up fivefold, while the population had only increased threefold.
A recent consultancy study by the French company, Generale des Eaux, showed that up to 40 per cent of treated water in Dublin was being lost due to leaks in the distribution network. This level of loss is being reduced with the aid of a £32 million conservation programme.
