However, homes that are found to have excessive lead levels in their supply will be told of this during the fixing of leaks and testing of local supplies, the utility provider said.
The comments come after reports that local council inspections have found schools, shops, and offices have had their supply contaminated.
Research compiled for the Environmental Protection Agency showed 41 different businesses and homes had excessive lead levels in their water in 2012.
Water charges for homes will come into effect in October with the first bills arriving in letterboxes in January.
Irish Water said yesterday that despite the fact it took over the control of water supplies from the beginning of this year, it had no responsibility for fixing old pipes that might contaminate water.
Elizabeth Arnett, Irish Water’s head of communications and corporate services, said: “No more than Electric Ireland would go in and rewire your property, the water utility wouldn’t go in and replumb the property.
“Our obligation is to make sure that the water we provide is safe, that our network is as lead free as we can have it.”
The EPA confirmed that schools in Cork, Waterford, and Sligo had been found to have excessive levels of lead in their water supplies following the introduction of stricter standards last year.
Old lead pipes where the chemical dissolves into the water supplies is causing the problem.
This can be dangerous for young children, pregnant women, and elderly people, in particular if the lead gets into their bodies.
“If your property has been plumbed prior to 1960, maybe late 1960s, the instances of lead is higher within the private property,” Ms Arnett told RTÉ radio.
Irish Water said it was not aware if the lead piping had been fixed since the random inspections of homes and businesses in 2012.
It said it would take 250,000 samples of water supplies this year and would notify customers if there were concerns about levels of lead.
The company yesterday also addressed reports that up to 600,000 people may be left without out-of-hours cover across six local authorities.
Ms Arnett denied that this was the case, insisting that staff will react to emergencies.
While some services were reduced because of cutbacks, there was “a difference between dealing with an emergency on the system or providing a continuous service”, she added.
However, confirmation that water services will be restricted outside of business hours and at weekends in Galway, Laois, South Tipperary, Leitrim, Westmeath, and Wicklow angered local politicians.
South Tipperary Independent TD Mattie McGrath said: “This disparity is infuriating and will simply confirm to people that Irish Water is a tool of Government to extract revenue while leaving the most basic services under-resourced or non-existent as the case is here.”