HRV Clean Water Limited has been fined $440,000 after pleading guilty to making unsubstantiated claims about the benefits of its water filters and also for making misleading claims about the quality of New Zealand's home water supply.

The fine was issued by Judge John Macdonald in the Auckland District Court on 19 October for claims made in promotional material between 2 July 2014 and 12 October 2017.

The unsubstantiated claims related to the ability of a magnetic 'ioniser' in its water filter systems to soften water, which would in turn help to relieve drinkers of skin conditions, such as eczema and dermatitis.

The claims made included statements such as "reduces skin irritations, dermatitis and eczema" and "removes existing lime scale and extends the life of your appliances."

Commissioner Anna Rawlings said the company did not have reasonable grounds to make such claims.

"HRV relied heavily on the information provided by the supplier without getting this verified by an expert," Rawlings said.

"Although HRV had some testing done, the results did not provide a reasonable basis for the various claims it had made – and continued to make – about the benefits of using the filters."

HRV made further misleading representations about the quality of the water and about the additives in New Zealand's home water supply.

This included the claim that "90 per cent of our waterways are polluted below swimming standards, yet this is where we source our water from", and that the filter would "remove many of the additives, as well as funny tastes and smells from your water supply."

Rawlings said these misleading statements likely created concern among consumers.

"The impression that a reasonable consumer would take from these claims is that without treatment, using the water supplied to New Zealand homes carried health risks. This was not true," she said.

Rawlings added that a water filter is an expensive and technical product and that consumers should be able to trust claims businesses make about the need for them.

The onus is on traders to ensure that they have the information they need to back up the claims they make and that they do not overstate the need or potential benefit of their products or services," Rawlings said.

In a statement released this afternoon, HRV said that it accepted the findings and the fine imposed.

The company said it has taken steps to address the concerns and remove any inaccurate information.

"We also put in place additional processes to ensure tighter control over marketing material in the future," the statement said.