TO when water is heated its mineral composition changes and often times becomes smelly.An example of this would be the water in a radiant heating system. This would be especially true for well water. I am on well water that is extremely hard( mineral content). Try a water softening system. This will kill the bacteria like ray has said and balance the minerals,and filter the water. It will taste better to drink and not be as harsh on you, your laundry and appliances.