The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.
How we test cleaning
An overall rating showing how well the detergent removes a range of stains including tea, dried egg yolk, baked-on milk and pasta starch from cups, glasses, plates and baking sheets.
How we test preventing filming and cloudiness
How well the detergent prevents streaks and residue from building up on plates, glasses and crockery over multiple washes. The best detergents will keep items clear and streak-free wash after wash, but the worst will allow a white film or discolouration to form.
How we test preventing water marks
How well the detergent prevents watermarks and droplets on dishes.
How we test anti-dullness
How well the detergent prevents knives and pans from dullness, loss of colour or discoloration.
How we test environmental impact
Whether these detergents contain chemicals that have any negative environmental effects. This includes if they are biodegradable, harmful to aquatic life or persistent which means the chemicals could linger and accumulate in waterways. In addition we examine the packaging material to see whether it's recyclable or made from recycled materials, and we also consider if refills are available.
