Originally Posted by boredatwork
Hard and soft water refer to water hardness. The connection you are referring to is pH and Alkalinity, not Hardness. Alkalinity is a pH buffer not Hardness. Hardness and pH are two independent things.
Right, but hard water often has alkalinity, no? I admit I have not been brewing for long, but I have a koi pond and often deal with water quality issues. From what I understand, more often than not hard tap water is due to calcium carbonates etc, which do impart alkalinity. I guess my question is, what accounts for hard tap water that doesn't have alkalinity?