David said more and more people were making their own kombucha at home for a fraction of the price.
"It probably costs 20-30 cents to make a bottle's worth. It's two tea bags and a quarter cup of sugar per litre to make a litre. That's about four bottles."
Kombucha has become huge business in New Zealand, with Countdown Supermarkets reporting sales almost doublingd in the past year.
Tauranga-based Good Buzz - New Zealand's biggest kombucha company - was founded in 2014 by Alex and Amber Campbell.
"Right now, we are doing up to 100,000 litres per month," says Alex Campbell. "Our goal is in the next six month to take it up to 200,000 litres per month."
It went from a small family operation, selling through farmers markets, to being stocked by 1300 retailers across the country.
Alex was a soldier in the American military, Amber a stay at home mum - but they left it all behind to start Good Buzz.
Brewing giant Lion New Zealand, has a 25 per cent share of the company, and said it was committed to offering Kiwis a healthier beverage choice.
"With mindsets changing around alcohol consumption, people want something as an alternative," Alex said.
"Kiwis are very social - we like having something in our hands when we're going to a barbecue, party or bar.
"The great thing about kombucha is you have that brewed aspect plus you tick all these boxes on health and well being and low sugar."
But just how healthy is kombucha?
Clinical nutritionist Ben Warren said people need to be wary.
"Certainly they have sugar in it," Warren said. "So you need to be aware of that.
"It's not a replacement for water as your primary consumption.
"You have to be aware it's not going to suit everybody.
"If you have a kombucha and you feel bloated or you get diarrhoea, or you have any kind of gut issue from drinking it, I would probably recommend it's not for you."
But as more and more people seek out alternative ways to improve their health, there's little chance of kombucha popularity fizzing out soon.
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