Water "up to 30,000 years old" has become a McCashin's signature ingredient for the Nelson brewery's beer, ciders and soft drinks.
Water assessed by scientists as being up to 30,000 years-old has become a signature ingredient in the beer, ciders and soft drinks made and bottled at Nelson's McCashin's Brewery.
Although the water was discovered on the property in 2009, it had not previously made economic sense to be bottling it for sale.
Emma McCashin, who fronts the family-owned business, said finding the water on land at the back of the brewery was exceptionally good luck, with a little help from a water diviner.
"We needed to find a second reliable water source and he came out, had a look at the mountains ... and did a few calculations and said, 'oh, if you dig deep here you'll come across the ancient palaeo water', and sure enough he was right," Mrs McCashin said.
She said it gushed like oil from a newly struck well.
The discovery coincided with her and husband Dean taking back the reins of the business, which is located in the original Rochdale Cider Factory in Stoke - the suburb between Nelson city and Richmond.
Mr McCashin's parents Terry and Bev McCashin bought the brewery from Rochdale Cider in 1980 when corporate giants Lion Nathan and Dominion Breweries controlled commercial production and distribution of virtually all New Zealand's beer.
The McCashins began brewing organic beverages and were ranked among the country's first craft brewers.
In early 1999 the family sold their beer brand to Lion under an agreement which meant they could continue to make the beer. Lion shifted the bottling to other outlets before it moved the entire production of Mac's Beer away from its home in Stoke.
The McCashin name was re-stamped on the product - now Stoke beer and Rochdale cider - in 2009 with the arrival of Dean and Emma.
Emma McCashin said they had planned to start bottling water then, but a tough economic climate meant Palaeo water had to wait just a few more years to see the light of day.
"We had the product bottled and ready to go but water is a luxury good, so there just wasn't the market for it at the time," Mrs McCashin said.
The water was instead used in making the established beverages - including the coffee sold at the brewery cafe.
"When we first started we were on town supply and when we switched over to this palaeo water there was a distinct difference in taste."
Mrs McCashin said they once had to dump a batch of cider contaminated by too much chlorine.
"That was a big incentive to get off town supply."
The company trademarked the brand Palaeo, which referenced the geological timeframe it came from.
Mrs McCashin said the first batch of pure water was bottled before Christmas, and was now quenching thirsts around New Zealand and throughout Asia.
"With increased knowledge and awareness of how much sugar is in fizzy drinks, and how bad sugar is, the water category in supermarkets is growing," she said.
She said it had meant minimal adjustment to the plant, except the switch to bottling in arctic blue glass with a transparent label featuring a map of New Zealand.
"The interesting thing about bottling water is everything has to be exceptionally clean as you can't afford to have sediment going into crystal clear water."
Mrs McCashin said electronic monitoring tracked the 216 cubic metres of water they were allowed to draw weekly from the 350-metre deep bore.