A top Kiwi actress features in a $3.5 million taxpayer-funded ad campaign which National say deliberately smears the country's local councils.

Thor: Ragnarok and Hunt for the Wilderpeople's actress Rachel House lends her voice to the Government's campaign to get people on board with its three waters proposal.

"Imagine Aotearoa without good water – what a stink as place that would be," she said in the ad.

She then describes a number of scenarios where filthy water is creating distress for the cartoon characters depicted.

"That's why we've got a plan – because we're water's biggest fan," it goes on to say.

Those comments have been criticised by regional mayors, who are upset with the implication they are doing a poor job of maintaining their water assets.

Waimate Mayor Craig Rowley said the ad showed a complete lack of respect for local government.

The Government wants to give four regional entities responsible for the country's storm, waste and freshwater – that responsibility currently lies with the country's 67 councils.

Local Government Minister Nanaia Mahuta said the plan would ensure everyone had access to world-class water assets.

Local Government Minister Nanaia Mahuta. (Photo / Mark Mitchell)

But National's local government spokesman Chris Luxon said the Government was spending millions of dollars on trying to erode people's goodwill with councils.

"It's been done in bad taste," he said, adding that Mahuta was telling the public there was a big problem with all water infrastructure.

"The suggestion in those ads is that everything is broken and rubbish – that's not the case across all the country."

When asked about the ad yesterday, Mahuta told media they were to help ratepayers understand the benefits of the proposed water reform.

The Department of Internal Affairs wouldn't provide a full breakdown of the $3.5m spend

But a spokesman said the money pays for a campaign which will run until late this year.

"The … campaign was designed specifically to create a sense of shared responsibility and to look at the issues from a New Zealand-wide perspective."