Some people are paying $4000 or more for a water ioniser that's claimed to have therapeutic health benefits for diseases including cancer, diabetes and arthritis.
Kangen water ionisers are sold throughout New Zealand, with claims that the electrolysation of ordinary tap water gives it healing and disease-preventative qualities.
Alison Campbell, senior lecturer in biological science at the University of Waikato, says the process of electrolysation is a complicated one.
"It means that an electric current's been put through it and that would result in at least some of the molecules split into hydrogen and oxygen, and if the hydrogen ions come off as a gas then the water that remains will be alkalised to some degree - it will have a higher pH."
So what might the benefits of drinking alkalised water be? "Search me!" Campbell says.
"There have been some very small studies done. There was one with about 100 people which claims drinking alkalised water is better for you after exercise than drinking ordinary tap water.
"But I'd want to see that done with a lot more people to be confident of that result."
The supposed cancer-preventative qualities of alkanity stem from some "out there" claims by American Robert O Young, she says.
"He claimed that if body tissues are acidic then this is a good breeding ground for cancer and so making your body tissues alkaline will protect your body from that.
"And made quite a killing selling people baking soda that they could take which would change their body's pH."
She says the body already has "quite strong" mechanisms to hold pH within a range of 7.35 to 7.45.
"Your kidneys and your lungs between them do a really good job of making sure that that happens."
As to anecdotal evidence and testimonies from people who swear by Kangen water, she says that can you be discounted.
"Science goes with evidence and anecdotes are personal statements, but they're not evidence of anything."
Her best advice? Save your money and drink tap water.
