Older septic tanks will not be forced to upgrade to the latest Environmental Protection Agency (EPA) standards under the Water Services Bill, Minister for the Environment Phil Hogan said.
Mr Hogan said he may even introduce a grant scheme for householders whose septic tanks are found to be polluting watercourses.
Ireland has lost a case at the European Court of Justice and was now facing substantial fines.
Mr Hogan said the current EPA guidelines which dates from 2009, only applied to new builds.
He acknowledged that many septic tanks across Ireland were decades old and even some septic tanks dating from the 1980s or 1970s, or earlier, would not be subject to that particular EPA guidance.
He would wait, he said, until the results of the first inspections to assess whether a grant would be put in place.
Mr Ó Cuív also said the inspection system, based on a €50 registration fee, would not pay for itself.
He said the concern was that charges would be passed on to the householder.
Tardis Environmental can provide a great septic tank emptying and maintenance service.