It has also emerged the Oireachtas committee on water charges, to begin work next week, is likely to hear from carers and patients groups about the need and costs of using water.
Fine Gael TDs are split on whether customers should be refunded or if non-payers should be pursued for outstanding bills.
Mr Naughten (Ind) said he wanted answers on what would be the “administrative costs” in paying for refunds.
He said issues in deciding the funding of services going forward needed to consider how this might impact on water quality or how it might affect private water supplies and or those paying for waste water.
He said he would not decide on whether he backed a full system of refunds until those questions were answered.
Meanwhile, members of the new water committee, which will meet next week and agree its work, have said they expect a number of groups and experts to be asked to attend hearings.
Fianna Fáil sources said patients groups or carers would be asked to attend, so that their costs and need for water could be assessed.
Micheál Martin’s party also wants a cost analysis to be undertaken to determine how much a system of refunds would cost.
However, some party TDs privately say it would cost the Government more in the long term to go after non-payers than to refund charges.
Fine Gael sources say Irish Water’s financial chiefs will be asked to attend hearings, while other utilities, such as electricity suppliers, may also be asked to explain how they collect charges or pursue non-payers.
Economists are also expected to be proposed as potential invitees in order to determine how the collection or non collection of charges might alter general taxation collections.
Taoiseach Enda Kenny again refused to say yesterday whether he supported refunds or not.
He told Labour’s Brendan Howlin in the Dáil that this would be decided by the new committee as well as as by a follow-up Dáil vote on its recommendations.
He stressed that the expert commission had not recommended abolishing charges but of giving people special allowances.
Fine Gael ministers say that non-payers should be pursued for outstanding bills, while a number of Independent ministers, including those with the Independent Alliance, have said they favour refunds.