Washing machines in general heat water up to 90 degrees so most people wonder does the washing machines use hot water from the mains or does it heat the water so lets explain the process .. majority of washing machines are connected to cold water supply and it heats it during the wash cycle other washing machines take water from both cold and hot supply so the best way to find out if you didn't install the washing machine yourself is to look up the manufacturer specification in the booklet that came with your machine or you can ask the person who fitted it they will know whether is it only connected to your cold supply only or both hot and cold