Overall score is determined solely by cleaning performance. We stain white tiles with a NASA formulation of simulated faeces. We then apply toilet cleaner to the tile and scrub it with a sponge attached to a mechanical arm.

To assess cleanliness we measure the reflectance of the tile before applying the stain and again after cleaning. Each product is tested three times, with the results averaged for a final score.

Find out more about how we test toilet cleaners.