The Government and Opposition are at odds over why there still isn't a tax on Kiwi water being exported.
Thousands took to the streets of Christchurch at the weekend, demanding an end to offshore companies bottling water and sending it overseas.
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Before the 2017 election, Labour promised to put a royalty on commercial water usage - not just for companies sending it offshore, but anyone making money from the otherwise free resource.
"We were going to give all the money back to the regional councils, so it wasn't a tax grab - it was just a resource rental," Environment Minister David Parker told The AM Show on Monday.
"But that didn't survive the coalition agreement."
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Instead they're trying to find a way just to sting bottled water exporters, but that's hit a snag too.
"The international rules relating to trade that bind every country, including New Zealand, say that that acts as a subsidy for internal production... so if you're going to have an effective tax on the export of water that's actually for a real sum, you've got to do that on all bottled water - including that which is produced and consumed in New Zealand."
There is the option of charging exporters for "recovering process costs", said Mr Parker, but the amount would be "derisory" and not worth the effort.
National Party leader Simon Bridges told The AM Show even if the Government finds a way to do it that doesn't breach its international trade obligations, it'll get held up in a legal quagmire at home.
"As soon as you do something that looks like charging, and that goes to the ownership of it, you've got court cases, you've got a bunch of interests - obviously iwi, Māori interests - you'll be in the Supreme Court before you could say, 'My name is Simon.' That's sort of what you're dealing with."
He's not opposed to a tax in principal, just doubts it can be done.
"I think most New Zealanders would agree, talking water bottling for export, there should be some way of New Zealanders getting something back on that. But here's the problem - it's really, really difficult."
He suggested the Government isn't trying very hard to get it across the line.
"These guys said it was easy, they said they'd do something. But hey, why deal with this? Why deal with other water issues when you can do some virtue signalling on other stuff?"
Mr Parker said they're not giving up just yet, and expect to have something in place before the 2020 election.
"It's not guaranteed. It's likely, but the amount of it depends on whether it's an export-only charge, which has to be very low, or whether you charge a cent a litre for everyone. Maybe a cent or two on every litre of bottled water would be fair - it could kick up a bit of extra money for councils and they could reduce their rates or clean up our rivers."