Households that paid the Irish Water bills will receive refunds of up to €325
The Taoiseach has said the Government plans to refund all water charges by the end of the year.
Charges have now been suspended for more than a year, with the Dáil having effectively abolished the controversial household charging regime.
Customers who paid all their bills will receive refunds of between €200 and €325.
It has been reported that just under one million households paid or partially paid the bills, and a total of €170 million is set to be refunded.
In an interview with The Sunday Independent, the Taoiseach said: "There's a cost. There are logistical issues as to how it's going to be done by Irish Water. And it may also require legislation. But we intend to do it in the autumn."
He said the repayments will not be part of the upcoming Budget, with refunds to begin before the budgetary measures are announced in October.
Mr Varadkar added: "We'll do it and have it under way. I anticipate that everybody will have their money back before the end of the year."
An Oireachtas committee earlier this year recommended that charges should be abolished except for excessive use, and domestic water use should be funded through general taxation.
The committee's report also calls for a referendum on public ownership of water services.