text: why does hot water clean better than cold water?   first, this is a chemistry question, not biology.  second, any solvent can hold more in suspension when it is hot.  basically, hot water can dissolve more detergent, and more detergent can pick up more dirt particles.  third, any substance like oil or grease will have a lower viscosity at higher temperature and therefore flow more freely. this will allow the water to rinse it away more easily, independent of detergent. that's why you run hot water to rinse greasy pans; otherwise, the grease would tend to accumulate in the drain pipes and cause a clog.  note: if your question is about sterilization, only water above 180 degrees farenheit will do the trick.