"The question you should ask yourself is, why haven't we brought forward other water projects that need to be done? If there is no need for these projects at this time, there is no need for a water rates increase," Mr McLachlan said.
Mr Halse said there would be about $8 million to spare in the water rates account by the end of the year, even as work on a new $18.7 million water treatment plant at Whau Valley continued.
"If we're not doing the work, the ratepayers should ask for their money back, that's how it works," he said.
However, WDC's group manager for support services, Alan Adcock, said the fact some spending from the water account had been deferred was to do with the timing of consenting and designs.
"In the meantime the money is coming in and is building up, but it's going to be spent [on water]. It's in surplus now, there's other times it's been in deficit," he said.
He said the water rate was increasing slightly as that money would be needed in the long term for water projects.
Meanwhile WDC's finance committee chairwoman, Shelley Deeming, described the overall annual plan as "steady as we go".
General rates looked set to rise 3.9 per cent year on year, as opposed to the 4.45 per cent predicted, due to a low local government inflation rate.
WDC also had to defer some capital project after the planned $10.2 million Old Boys' Rugby Club sale was blocked in court.
- The annual plan is online at wdc.govt.nz.