Labour MP Mr Nash has been calling for a levy on commercial water use since 2015 - sparked by the opening of the $20 million Miracle Water bottling plant in Hastings.
He said he was "very pleased" with his party's policy, which would mean the 11 companies with consented water bottling takes in Hawke's Bay would be charged an unspecified royalty.
"At my street corner meetings it always comes up," he said, "no one understands the logic behind this not charging for water companies, giving our water away free to bottling companies."
The revenue from these royalties would go to Regional Councils to be spent on waterways.
"The majority of the money will come back for the local region, so the money isn't going to disappear into some big hole that is the government coffers," he said.
"It's a way for us to leverage off our brand of fine wine and great food in a way that's sustainable and delivers economic benefits for the region."
Napier Green Party candidate Damon Rusden also welcomed the policy. His party proposed a water charge prior to Labour, and wants it set at 10c per litre for water bottling companies. The rate for other industries would be set after consultation.
"This is a united front with Labour and Greens. We're 100 per cent behind them and what we're seeing now is a dramatic shift to protect our environment, and protect our rivers like never before, and New Zealand needs a change of government to do that."
He noted the Greens policy also had a focus on water infrastructure, which this charge would be ringfenced for.
"The Greens realise that the source of the problem is cow numbers and that we need to farm smarter with less cows because anything that doesn't reduce herd numbers is going to repeat itself."
Ms Ardern has said Labour's water price would not be as high as 10c for any industry.
National Party Napier candidate David Elliott said he supported charging water bottlers, "so long as it was specifically that".
However, he said this policy was a tax on all water users which would increase the costs of everyday goods.
"It would be a disaster for the Hawke's Bay economy, a food and wine-producing region," he said.
"People need to be aware that this new tax increases the cost of living for everybody, hurting those that struggle already, but provides no details on who really gets all the money or who are the recognised owners."
Mr Nash said the charge would be different across sectors, and it had been assured it would not mean the primary sector was not profitable.
"We don't want people to go, 'oh my god this is going to mean I'm going to go broke', that is not the aim at all, its to really drive efficiency, but also recognise that our water does have value."
Democrats for Social Credit candidate Karl Matthys could not be reached for comment.
