One of the more expensive laundry detergents has been described as "worse than water" in a Consumer NZ test that found it didn't remove any stains.

The tropical scented Re.stor Concentrated Laundry Detergent Sheets performed lower in recent tests than a water-only wash and landed the product on the Consumer NZ "do not buy" list.

The other laundry liquids not to make the grade included budget branded Essentials Laundry Liquid (2L) and Value Laundry Detergent (2L).

Consumer NZ testers graded the detergents on how well they removed everyday grime, collar and cuff marks, blood stains, grass stains, olive oil and tomato residue.

The people behind Re.stor say they stand by their product. Photo / Supplied

All three were recorded as performing terribly with all stain removal and had no positive qualities listed.

But the chief operating officer of the Kiwi-owned Re.stor has hit back at testing and said she stands by the product.

Renee Lee said she was shocked at Consumer NZ's findings and didn't believe testers had used the new product correctly.

"We have done rigorous testing, gathered extensive consumer feedback that has rated us 4.5/5 on cleaning effectiveness and the factory consistently independently tests performance," Lee said.

"Clearly it's a case that it's a new innovative product where they don't know how to use them and have not followed instructions on how to use.

"For a regular load they should use two sheets and as they haven't published how they have tested then we do not know if they even put them in the drum or not."

Lee said there was "no physical way we can be worse than water given mixing our sheets with water is part of the washing process".

"It's just not logical and it just feels like they are hunting for a headline."

Testing also ranked price but not price per wash Lee said. The Re.stor pack for $12.50 was for 60 washes and was compared to smaller boxes that cleaned 12 loads.

"It is cheaper per wash than others it has been compared to."

Lee pointed to live Instagram feeds that showed coffee stains, make-up, and self-tanner being removed.

The top performers in the Consumer NZ tests included Persil original powder (1kg), Dynamo Professional Oxi Plus (1.5L) and Ecostore Extra Clean Laundry Powder (1kg).

The highest-ranking product, Persil With a Touch of Comfort (1kg), cost on average $6.49.

Consumer NZ said the Re-stor product was more expensive than the top laundry performer, costing $12.50 on average.

"Not all laundry detergents are created equally, and our testing found there is a broad range in performance," said Consumer product test team lead James Le Page.

"Our top detergent scored 91 per cent while our lowest scraped in with 26 per cent performance.

Le Page said when selling laundry detergents companies used 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 tester James Le Page found price and performance of laundry detergent were not always linked. Photo / Supplied

The testing of 55 laundry cleaning products, both liquid, powder, capsule, and sheet, found there was little correlation between price and performance.

The review also found there was no consistency within brands.

EcoStore Lemon performed badly with the only good point noted that it was good at removing blood stains.

EcoStore Extra Clean however performed well with good or excellent stain removal as well as being inexpensive per wash.

The testing did not analyse environmental impact but Consumer NZ does state some products have less environmental impact than others.

This is because they recommend lower doses, and leave 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.

Consumer NZ pointed out there was no completely environmentally friendly detergent.

"All place a burden on the planet, in the materials, they release into our wastewater and in their manufacturing and packaging."

Manufacturers can back their claims by applying for accreditation to an environmental labelling scheme.

Environmental Choice is endorsed by the Government and provides a credible and independent standard to guide people who want to purchase and use products that are proven to be better for the environment.

Some laundry detergents tested by Consumer NZ ranked "worse than water" with a warning not to buy. Photo / File

Tips for dealing with a tricky wash

• Increasing the dose above the recommended level will get really dirty clothes cleaner but it won't make much difference in a normal load.
• A warmer wash could help when something's really grubby but check the garment's care label first. Higher temperatures soften dirt and oily stains, making it easier for the mechanical action of the washing machine to remove them.
• Cold washes are just fine for regular washing and they save on power bills.
• Pre-soaking clothes can improve the results of a normal wash. This helps loosen dirt so it can be removed more easily. Check the care label first.
• Wash your whites separately, because dye can transfer between clothes during the wash.

To see the full results of the Consumer NZ laundry testing click here.

- by Kirsty Wynn, NZ Herald