A test has found what laundry detergents consumers should avoid, finding some popular detergents are "worse than water".
Consumer NZ has put laundry detergents to the test, finding more expensive detergents weren't necessarily better.
Landing in the 'do not buy' list was Essentials laundry liquid (2L), Value laundry detergent (2L) and Re-stor concentrated laundry detergent sheets tropical breeze (60 sheets) - which Consumer NZ found all rated lower than a wash with only water.
Despite being one of the worst performers, the Re-stor product was more expensive than the top performer - costing $12.50 on average.
Taking out the top spot for best laundry detergent was Persil with a touch of comfort (1kg), costing $6.49 on average.
Other top performers included Persil original powder (1kg), Dynamo professional oxi plus (1.5L) and Ecostore extra clean laundry powder (1kg).
The detergents were graded on how well they removed everyday grime, collar and cuff marks, grass stains, olive oil and tomato residue.
"Not all laundry detergents are created equally and our testing found there is a broad range in performance," said Consumer NZ product test team lead James Le Page. "Our top detergent scored 91 percent while our lowest scraped in with 26 percent performance.
"Laundry detergents can have persuasive marketing, with everything from 'natural elements' to being an 'odour fighter' or 'plant-powered.'
"Our advice is to look for independent results to find out how well a detergent performs."
Consumer NZ said despite some detergents claiming they are environmentally friendly, they all place a burden on the planet.
There's no such thing as a completely environmentally friendly detergent because of the impact they have from their manufacturing and packaging to the materials detergents release into wastewater, Consumer NZ said.
However, some detergents have a less environmental impact than others due to recommending lower doses and leaving out ingredients that don't contribute to washing performance or those that may harm the environment. Ingredients commonly targeted are phosphates, enzymes and optical brighteners.
Manufacturers can back their claims by applying for accreditation to an environmental labelling scheme.
Tips for dealing with a tricky wash
Consumer NZ's tips for getting the best wash include only increasing the dose above the recommended level to clean really dirty clothes, it won't make much difference in a normal load.
A warmer wash can help soften and remove dirt and oily stains and pre-soaking can also help loosen the dirt, it said. However, consumers must check the garment's care label first to make sure it doesn't ruin the item.
Consumer NZ said cold washes are just fine for regular washing and they save on power bills.
The organisation also urges consumers to always wash their whites separately because the dye can transfer between clothes during the wash.