Environment Minister John Gormley announced that almost half of the special funding would help authorities with running costs for recently completed facilities.
The remaining Euro 13.4m will pay for other expenses such as water and wastewater sampling to ensure authorities are meeting water quality standards.
It follows record grants of almost Euro 1bn earlier this year to local authorities to spend on a variety of their services.
Government said that in recent years, there have been record levels of investment in new water services infrastructure in Ireland.
"The new infrastructure and improved water and wastewater treatment standards are key steps towards ensuring that Ireland's drinking water and water in the environment are of the highest quality," Mr Gormley said.
The Euro 10m funding towards the cost of operating new treatment plants is double what government provided in 2007.
The other Euro 13.4m is an extra boost which was not provided last year.
As well as funding monitoring, it is also intended to fund licence applications to the Environmental Protection Agency for wastewater discharges, and compensate local authorities for special water charging agreements for schools.
"I will expect all authorities to act responsibly and efficiently and in future to prioritise their own resources towards achieving high standards to protect public health and preserve water quality in our rivers, lakes and seas," Mr Gormley added.
The most recent figures from the Environmental Protection Agency show that 98.9% of public water supplies met standards for E. Coli in 2005.
The proportion of wastewater receiving secondary wastewater treatment increased from 21% in 2000-2001 to 82% in 2004-05.