Water experts are confident local authorities will be able to comply with new EU limits for lead in drinking water without having to resort to replacing all lead piping at a cost of £1 billion.
The Department of the Environment estimates that drinking water is supplied to 60,000 homes in Dublin and 20,000 in Cork city through lead piping. These pipes are the main source of harmful concentrations of lead in drinking water.
The EU is moving to reduce lead levels in drinking water as the metal can cause brain damage, especially to young children, and is also linked to birth defects and cancer. Under the 1998 EU water directive, the current maximum level of 50 micrograms of lead per litre is to be cut to 25 micrograms by 2004, and 10 micrograms by 2014.
There is very little naturally occurring lead in Irish tap water, but the metal is soluble and leaches into the water from lead pipes, according to the Environmental Protection Agency's environmental and planning programme manager, Mr Gerry Carty.
Lead has not been a major problem to date in the Republic, with just one breach of the EU limits among 4,500 samples taken in 1997, Mr Carty noted.
The problem is believed to be confined to the older sections of Dublin and Cork cities. A Dublin Corporation divisional engineer, Mr Peter O'Reilly, estimated that any house built in the capital before the 1950s was likely to be connected to the water main by a lead pipe, while they may also have lead piping to the water tank in the attic.
A 1995 EU report estimated the cost of replacing all lead water piping in the State at £1 billion. The cost of replacing piping in each house is believed to be between £300 and £1,000.
If all lead piping in Dublin had to be replaced, the corporation would face a bill of between £40 million and £60 million, Mr O'Reilly estimated, but this would only cover the cost of replacing the public piping. Householders in the capital could face a similar bill for the replacement cost of pipes on their properties.
The replacement costs in Cork city could reach £20 million, according to local Green Party councillor, Mr Dan Boyle, who has expressed concern about the issue.
Both Dublin and Cork Corporations are carrying out pilot surveys to assess the extent of the problem. However, the Department of the Environment believes lead pipes may not have to be removed in many cases.
Water samples collected in some of the oldest parts of Dublin city - where lead levels were expected to be highest - found that 80 per cent contained fewer than 10 micrograms of lead.
A Department of the Environment spokesman said a film had built up on the insides of the pipes, preventing the water from coming into contact with the lead.
A survey published in France this week found that 13 of 137 samples taken in Paris breached the current 50 microgram limit. In some samples, when the tap was initially opened, samples contained 510 micrograms of lead - 10 times the EU limit and 50 times the WHO's recommended limit.
However, the Department of the Environment will not have a clear idea of the extent of the problem or the amount of piping it will have to replace until the EU specifies the sampling method that will be used for the 1998 directive.