pH - pH is caused by the presence of carbon dioxide in groundwater having an impact by increasing the water's acidity & corrosive quality.  Low pH causes pinhole leaks in copper piping systems, premature water heater failures, the tell tale blue-green stains and overall water system degradation.  This is a very common condition caused by a lack of limestone within your local geology.  Acceptable ranges are 6.8 - 8.3 on a 0 - 14 scale with 7 representing neutral.  As pH levels drop below 6.8 the corrosiveness increases exponentially.  (if an issue, please note copper results)