The Environment Minister says opposition spokespeople are 'in cloud cuckoo land' over the scale of the task facing Irish Water.
It's after a new report by the utility showed Dublin will need the equivalent of an extra 215 Olympic-sized swimming pools of water every day by 2050.
The report says the capital, the east and midlands regions will need a new water source.
Irish Water is beginning a consultation period with a view to applying for planning permission in 2017.
Minister Alan Kelly says Irish Water needs funding to accomplish these tasks - and the opposition isn't facing up to the facts: