The Commission for Energy Regulation has approved the reduced water charges announced by the government last November.
This sets flat charges for water for four years from 2015 to 2018.
A single household will pay €160 while a two person or more household pays €260 per year.
Every household which registers is entitled to a €100 water conservation grant.
In a decision issued today, the Regulator has also approved some other small charges including a €100 fee for meter testing and €17 for a special meter reading.
It's also been confirmed that registration with the utility anytime during 2015 entitles customers to all allowances backdated to the beginning of the year.
Meanwhile, the Government has been requested to defer water bills until the Eurostat test on Irish Water is complete.
During Leaders Questions in the Dáil, Fianna Fáil Deputy Sean Fleming put it to the Tánaiste that the time scale for Irish Water to pass the Eurostat test was March, however the Taoiseach has said the status of Irish Water will not be clear until June.
Joan Burton said the delay does not change what is happening at Irish Water.
Deputy Fleming asked if the Tánaiste was seeking to undermine the Taoiseach in her comments.
He pointed out that Eurostat is training the CSO, which is under the Department of the Taoiseach, in order to meet the deadline.
Ms Burton said there was no difficulty that the CSO, which is an independent body, needed need to do more work or that it required more resources.
