Hard water will not cause any problems with the system. If you don't mind the taste of water with a lot of minerals (that's what hardness is), you will still get all the benefits of AquaLiv Water. Please feel free to ask follow up questions. Thank you.
Frank Allen Hi Frank, It's should only still need to be replaced once per year. Only if your flow slows down a lot, but I don't think you are at that level of hardness that the flow would be significantly lower after a year.