Seventy-two per cent of household arguments are about how to stack the dishwasher.
That statistic is made up, but you believed it, right? Because it's a safe bet 100 per cent of people think the people they live with put the cups on the wrong rack.
Science has quite a bit to say about dishwashers, first patented in 1866 by Josephine Garis Cochran (she was rich, she threw a lot of parties and she was sick of servants breaking plates).
Research published in the International Journal of Consumer Studies has determined machines are better than humans at dishwashing. When presented with 12 sets of tableware soiled with mince, porridge and other meals that cleaning nightmares are made of, dishwashers got everything slightly cleaner in just 13 litres of water. Manual labourers used 49 litres of water. (They also spent a full hour on the job, compared to the nine minutes it took to load and unload the machine).
How, exactly, should you stack a dishwasher? Another study reported in Science Direct recommends ignoring the natural rectangular configuration and arranging plates in a circular manner to maximise water flow. Dishes coated with protein - we're looking at you, poached egg - should go on the outside, where water velocity is slower, which gives the protein particles time to hydrate and plump before they're washed away.
Don't crowd your machine and (good news!) don't pre-wash, because in order for dishwasher detergent to work, it needs particles to stick to.
Scientists have yet to recommend a reliable method for determining whose turn it is to unload the dishwasher.