Scientific tests commissioned by Fair Go reveal a popular water filtration product for sale in New Zealand may not be meeting the claims it makes of being able to get rid of fluoride.
The product's distributor, Fill2Pure, says the results show New Zealand laboratories aren't up to scratch - but we're not the first ones to question the jug's ability to work miracles on minerals.
Customers Tim and Celia Hope purchased a Fill2Pure jug earlier this year in an attempt to filter chlorine and fluoride from their drinking water. They decided to have the filtered water tested after noticing they couldn't taste the difference between water from the jug, and water from their tap.
They were shocked to find the jug didn't appear to have removed any fluoride at all.
"It was very disappointing," says Celia Hope.
The couple sent the results to Fill2Pure's Natasha Lynch, who wrote back, stating that New Zealand laboratories are "so rudimentary they cannot provide an accurate fluoride reading".
The lab the Hopes used is internationally accredited, and is recommended by Fluoride Free NZ for fluoride testing.
Fair Go also used an internationally accredited lab to test another Fill2Pure jug, and got the same result - the difference between filtered and non-filtered water just 0.01g/m3 - that's within the measure of uncertainty, which is only 0.02g/m3.
The company disputed these results also, and referred Fair Go to the product's Californian inventor, Carl Palmer.
"We haven't even had a single claim," he says.
"This is the first complaint we've ever had".
Mr Palmer was also highly sceptical of the accredited laboratory results obtained by the Hopes and Fair Go.
"Are you telling me that our 18 sets of tests and our 61 different tests and 23 years of business without a single claim in 23 years, that we're wrong and your laboratory's correct with this set of tests?" he asked.
The laboratory used by Fair Go is accredited by IANZ, the organisation that oversees the international accreditation of New Zealand laboratories.
I DON'T THINK IT'S GOING TO TAKE OUT ANY OF THE FLUORIDE
Nanotechnologist Dr Michelle Dickinson says after examining the filter, she accepts it may filter chlorine - but only because it's a large ion.
"I don't think it's going to take out any of the fluoride," she said after pulling the jug and filter apart.
"It [the water] is flowing through too quickly. It just looks like a standard carbon system".
Dr Dickinson says fluoride is difficult to filter, can take a long time and requires more specialised technology than a coconut carbon filter.
Mr Palmer provided several lab reports to back up his claims of fluoride removal, but many were for a range of other tests, not fluoride, and our research could not find any evidence of those labs being accredited to test for fluoride in drinking water.
Fill2Pure's New Zealand distributors, Matt Hall and Natasha Lynch, say the filter in their products works on a wide range of "contaminants, including fluoride".
However they agreed to refund the Hopes, and provide a replacement jug.
The jug's inventor, Carl Palmer, has vowed to have more fluoride testing on his jug - this time done by a New Zealand laboratory.