A.Master plumber Rex Cauldwell responds: With a pH of 6.2, your water looks at copper and says yum, yum. You need an acid neutralizer, which passes the water through a container with neutralizing media. Look for an acid neutralizer with a capacity of at least 1 cubic foot of media. Acid neutralizers are available from many plumbing supply houses or from Sears. Plumbing supply houses can test your water and help spec the unit for you.
Acid neutralizers are either passive or active. A passive model, sometimes called an upflow, just sits there as water flows through it. Debris, iron, and other junk will collect in the media. In a passive model, the media tend to turn into a concrete-like mass after a while.
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