Buyer beware - bulk bins are not the bargain you may believe.
Despite what many consumers may assume, the Herald found packaged products were almost always cheaper than their brandless, bulk bin counterparts and some were just a fraction of the price.
Of the sixteen products compared at New World Victoria Park, Pak'n Save Mt Albert and Countdown Ponsonby, only sunflower seeds were cheaper loose, and only at Countdown where they were on special.
At 27 cents/100g, packaged Pams oats at New World were less than half the price of loose oats, and Pams red lentils were nearly two thirds cheaper to buy in a packet (36 cents/100g).
The story was the same at Pak'n Save, with loose oats selling for nearly twice the price of packaged oats.
At Countdown, red lentils were a third cheaper pre-packed: 66 cents/100g compared to 99 cents/100g loose.
In each case the Herald sought out the cheapest packaged option available. Where different sizes were available, smaller packets tended to have higher prices per 100g.
Wellington woman Patricia Thompson was shocked to discover the price difference when she began embarking on a zero-waste lifestyle earlier this year.
Each week she tries to buy her basic groceries in bulk and take them home in reusable containers.
She had always assumed this would be the cheaper option, but after starting to compare prices realised this was not the case.
Every product she had checked so far was more expensive from a bulk bin.
"I was very surprised," Thompson said.
"You assume if you're doing your own packaging it's not going to be as expensive."
Thomspon thought supermarkets should bring down the cost of loose food to make buying unpackaged goods "an even playing field".
"If they're going to be serious about reducing waste they need to not be charging people more for loose items," she said.
Zero waste campaigner Hannah Blumhardt said although she could see why people would assume bulk food would be cheaper, bulk buying was not a competitive market and so prices didn't need to be low.
Blumhardt and her partner, Liam Prince, have been waste-free for two-and-a-half years and teach others, like Thompson, how to live waste-free as well.
"One thing [we] have found, after living without throwing rubbish away, is how thoroughly normalised disposability is in our society,' she said.
"As a result, major grocery outlets have little incentive to really encourage or cater to less wasteful shopping."
Representatives for both supermarket brands said prices reflected that the quality in bulk bins was often higher than packaged items, and self-service-style added extra hygiene costs.
"With bulk bins there are additional costs for supermarkets to maintain health and safety, manage product wastage due to cross-combination between bins and the spills arising from self-service," said Countdown spokesman James Walker.
Foodstuffs NZ spokeswoman Catherine Reiss said nowadays people shopping in so-called bulk bins were usually looking to buy in small quantities for recipes or single servings.
"It's one reason the bins are [now] more commonly referred to as Self Selection."
Others liked to be able to inspect loose products and these shoppers valued quality over price, she said.
Foodstuffs owns New World and Pak'n Save supermarkets.