The move away from single use plastic bags is gaining momentum - but makers of non-plastic compostable bags say they're struggling to get certified.
Countdown's first 10 supermarkets will going plastic bag free on Monday and the remaining 172 stores will follow by the end of the year, while a Nelson supermarket is supplying only paper bags in its fruit, vegetable and bulk buy aisles.
The Warehouse Group is the latest to announce it is scrapping plastic bags, and intends replacing them with compostable bags in its 254 stores by the end of the year.
But makers of non-plastic compostable bags say they are still struggling to get the right certifications because current standards favour bags produced using petrochemicals.
Chris Heaten of ComPlast bags told Jesse Mulligan his entirely organic, petrochemical-free, compostable bag does not make the New Zealand standard.
His bags are made from a combination of vegetable products, primarily kasava root starch.
Heaton says they fully decompose in 45 days in controlled composting, and are 85 percent "back to nature" in 84 days in "ambient conditions".
They produce no micro-plastic particles, because they contain no petroleum, chemicals or added minerals that would create the particles during degradation.
Heaton is frustrated however that one element of the standard is preventing him getting his bags to a wider market.
New Zealand has adopted the Australian standard, which is a good one, he says, but one requirement is problematic.
"To comply, 90 percent needs to disintegrate to particles smaller than 2mm in 12 weeks."
For his product that is a problem - but only just.
"When you've got a product made out of truly organic matter, achieving that is a little difficult. Our product achieves 85 percent not 90 percent.
"When you have a petroleum-based [product], or some sort of blend, you can achieve that. The standard is set up to compost quickly versus to compost 100 percent."
This bias towards rapid disintegration in the standard causes most products to produce accelerated rates of micro-plastic which then enter waterways and food sources, he says.
And just missing that standard means he has problems getting his product to the big retailers.
"Large organisations that are looking for solutions … are fearful of taking on a product that does not have the standard and does not comply."
Heaton says the range of uses for his bag, as a replacement for current petrochemical-based bags - is huge.
"Everything from airlines collecting rubbish, dry cleaning, rubbish collection, dog waste collection."