Many people run their washing machines almost exclusively at 40° (or even lower) these days in a bid to save energy and money. Those of us who took home economics at school will have learnt that the hotter the water, the better the wash - but will generally have ignored it in this case because our clothes kept coming out of our machines looking clean and we saved ourselves a few quid in the process. However, it isn't just your laundry that gets washed when you run your machine - the inside of the machine does, too. The consequence of these repeated cooler washes is that a residue of not-quite-dissolved washing powder, limescale, dirt, grease and bacteria are left inside .  Read the complete review