A damning report on kids' tooth decay has prompted renewed calls for more regulation of sugary drinks and junk food.

The author of the Child Poverty Action Group report, dentist Dr Rob Beaglehole, is calling for a tax on sugary drinks and for the Government to force schools to only provide water.

Dr Beaglehole says alerting people to the dangers of sugar has not worked - and tooth decay is a hugely pervasive problem.

"The number one reason children get admitted to hospital here in New Zealand is actually to have their teeth taken out under general anaesthetic. Every general anaesthetic we give children costs the taxpayer $4000."

He is calling on Education Minister Chris Hipkins to urgently adopt a water-only policy for schools.

"It would go a long way to help raise the awareness about the dangers of sugary drinks. It doesn't make any sense to be selling sickness to kids in schools."