7:39 pm today

Wellington Mayor Andrew Little believes the new water entity will need to go back to the drawing board on a new business case.

A half-a-billion dollar price-tag for rolling out water meters in Wellington is not "credible", says the mayor, and he expects the new water entity to start from scratch on a business case.

Tiaki Wai will manage the region's water services from July, and says it wants to roll-out about 140,000 water meters to help people manage consumption and identify leaks.

Its draft strategy said installing meters could take between five and seven years, and may cost $500-590 million.