These filters don't actually get rid of hard water. Are for chlorine and sediment and help with the taste and smell. You will need a water softener. You may have one for the house already but not all of the water is softened depending on how it's hooked up. Most outside hose faucets aren't connected to the water softener. And if you have a water softening system it sounds like the water line to the fridge is not connected to that system.