Commercial users of water would have to pay a royalty under a Labour Government - and farmers aren't exempt.
Labour leader Jacinda Ardern just launched the party's freshwater policy, with public concerns about water quality and allocation at fever pitch.
The royalty would capture bottling companies - and irrigation schemes.
The consumption royalty would not hit hydro-power schemes.
Bottlers would pay per litre and the yet-to-be set royalty for irrigation water will be based on per 1000 litres.
But it will be flexible to reflect drought or very wet areas.
Ms Ardern says the levy would be "proportionate and fair" but pledged to meet with all groups affected by holding a "roundtable" in her first 100 days of office.
Households and councils would be exempt. And the money would be used to "assist" with cleaning up polluted waterways. It would largely be redirected to regional councils.
The party wants nationwide standards with a goal of making rivers and lakes swimable "within a generation".
Farmers are in the gun with requirements to reduce stock and fence off waterways - with "more sophisticated farming methods that rely less on ever higher stocking levels".
But they'll get help with fencing and riparian planting through Labour's proposed Ready for Work scheme. That policy sends young people, claiming the dole, out to work.
Ms Ardern made the announcement at the Environmental Defence Society conference in Auckland today.
"Clean water is the birth-right of all of us. I want future generations to be able to swim in the local river, just like I did."
"All our children deserve to inherit swimable lakes and rivers – and they can, if we commit ourselves as a country to cleaning up our water," she said.
National have asked an expert group to look at water pricing - but it's not due to report back until after next month's election, in December.
Environment minister Nick Smith yesterday committed $44m out of a $100m fund to clean up 100 toxic lakes and rivers. He claimed a levy on water would wipe out the dairy sector, costing it $600 billion.