How we test dishwasher detergents

The overall score is the average of the six scores for removing stains caused by:

• egg yolk
• rice starch
• baked-on cheese
• red wine
• coffee
• minced meat.

About our test

We test in a controlled lab environment using a standard dishwasher designed for domestic consumers, set to a standard “normal” cycle. Each detergent is tested four times on each type of stain. The stained tiles we test with are used by consumer organisations and manufacturers all around the world to simulate everyday food stains. To assess how well the detergents have cleaned, we measure the reflectance of the tiles with a spectrophotometer before and after cleaning.

Other ratings

We also assess product packaging and claims made on the product packaging. We award a rating of good, acceptable or poor. These assessments don’t contribute to the overall score as they’re primarily based on claims on the packaging.

Packaging: Assesses what the packaging is made of, how recyclable it is in New Zealand, and how clearly it’s labelled with recycling information.

Environment: Considers whether the product claims to be biodegradable, septic-tank safe or grey-water safe, and if a standard is cited. We also consider if there are unfair green claims, such as being phosphate free.

Safety: We look at whether the packaging has important safety information, such as the poisons centre phone number, or instructions on what to do if it is ingested or gets in eyes or on skin, and if the ingredients are listed.