More than 10 years after a major report identified an "unjustifiable" leakage rate of 47% in the country's public water system, the latest figures show that the rate has dropped only marginally to 41%. This is despite an investment programme of €5bn announced in 2004.

The figures are revealed as local authorities in Dublin, Cork, Galway and the midlands predict further water shortages this week with reservoirs likely to remain critically low.

Leaks, following the post-freeze thaw, in the public mains supply, and the subsequent increase in demand, are blamed for the drop in levels in the reservoirs. Now experts fear that the freeze may have produced even more leaks in the last few weeks, further weakening a system much of which dates back to Victorian times.

A leading water engineer warned that spending on repairs and replacement of the pipes and joints must be "significantly geared up" or else the country would endure further water shortages.

"There has been a significant improvement in funding in the last 10 years but the recent experience has shown that much more needs to be done," said Kevin Murray, chairman of the Cork region of Engineers Ireland, which will hold a day-long seminar on flood prevention in Dublin this Thursday.

"Leakage control has to be prioritised over capital projects such as treatment plants. It doesn't make much sense to put millions into water production plants if nearly half of it is being wasted before it gets to the taps. If we can reduce the leakage rate from 41% to the EU norm of 25% then we won't need as much investment in plants," said Murray.

A spokesman for environment minister John Gormley said last week that, despite the cutbacks, the department had increased its allocation for the water-service investment programme from €500m last year to €520m this year and that this would be concentrated on mending and replacing pipes rather than constructing water plants.

The 2000 National Water Study by engineering consultancy firm WS Atkins identified an average leak rate of 'unaccounted for water' (UFW) of over 47%. The largest source, according to the study, was "leakage from the underground distribution system".

But according to the most recent figures from the local authorities, the UFW level stands at over 41%, ranging from a low of below 17% in the area under Limerick County Council's management, to a high of almost 60% in Roscommon. Kilkenny, south Tipperary, Cork and Offaly all of which have UFWs in excess of 50%.

"If we continue to spend as we do now, it will take a lifetime to repair the system. We need to gear up spending," said Murray.

He agreed that domestic water charges and metering would improve matters but primarily by identifying hidden leaks in houses rather than reducing domestic demand.

"As metering will take some time, a fixed charge will probably be introduced first. Based on current non-domestic charges this would work out at €500 per year per household of four," he said.