Kmart's "low prices for life" have been called into question by Consumer NZ, who were left with a blender that dripped green-black liquid after they put the product through its paces.

They tested the $29 Anko blender and found that, as well as the dripping liquid, the blade worked itself loose - and called into question the useful life of the product.

Consumer NZ product test manager Dr Paul Smith tested the blender by using it to make his daily smoothie of frozen banana and mango, spinach, yogurt and matcha powder.

Within a week the blade had worked loose from its housing and green-black liquid had begun to drip from the base of the jug.

"A blender showing signs of failure in its first week is concerning, but what's worse is Kmart's failure to offer a repair. The blade is removable for cleaning, so it would be very easy to replace. But there are no repair parts on offer, so at the slightest sign of failure it needs to be tossed," Smith said.

"For companies focused on low prices such as Kmart, it's cheaper and easier to replace an entire product rather than fix it. The few that fail within warranty hit Kmart's bottom line, but the majority that hang on just a bit longer don't cost the retailer a cent. There's no incentive to make products that perform beyond a year or two."

Consumer NZ reported that Smith asked Kmart for a replacement part for the blender and was told no parts were available, being offered a refund instead,

"That's not good enough," wrote Smith.

"I don't want to junk an otherwise fine appliance because one small, easy-to-replace part has failed."

The Herald has contacted Kmart for comment.

Smith said that companies that sell cheap, unsupported appliances have a responsibility to consumers to make more durable products - and to the environment to avoid e-waste.

"Through our Built to Last campaign, we are challenging manufacturers to make more durable and repairable appliances and to provide spare parts at a reasonable cost. We're also changing the way we conduct our testing to introduce reliability scoring, helping consumers to be informed about product durability when purchasing a product," Smith said.