DATA Commissioner Billy Hawkins has revealed his office is working with Irish Water to make sure it does not breach privacy rules when billing households.
Mr Hawkes said the utility company has been landed with a Government policy to give extra allowances to tens of thousands of homes with children when charging, but has no way to check them.
People with certain medical conditions, as well as old age pensioners, carers, and households on benefits, are also expected to be given extra allowances.
He called for all agencies, like Irish Water, to carry out privacy impact assessments to ensure they are not breaching a person's right to privacy.
"We are working closely with Irish Water in terms of how they charge people," Mr Hawkes said.
"Basically there will be an allowance for children, but they [Irish Water] have to establish are there children in a house."
Irish Water has previously said households will be called on to self-declare any allowances they may be entitled to.
Mr Hawkes, who steps down next month, spoke out during a public interview with the Centre for Irish and European Security.
He warned that the State has more information on citizens than any other organisation, and in particular information relating those people in disadvantaged communities.
"The greatest amount of intrusion by the State is on people who are poor," he said.
"They are often means-tested and have to give all sorts of information. They are also subject to suspicion of fraud."
He said particular focus has been paid to the Department of Social Protection, which holds information on people in receipt of child benefit, a pension or unemployment benefits who will often be questioned and "asked to justify" themselves.