Blue-green stains on plumbing fixtures, showers, tubs, faucets and drains, and possibly pinhole leaks in copper plumbing, but the pH is neutral.
High dissolved oxygen, poor plumbing practices (excessive flux, improper de-burring of copper pipes), improper electrical grounding, excessive sand or sediment and/or high velocity flow rates. In a high percentage of the cases, the source of the corrosion may not be determined.
Though a small amount of copper is required by the human body as an essential nutrient, long-term exposure to elevated levels of copper in drinking water may cause serious health problems. Short periods of exposure to high levels of copper can cause gastrointestinal problems, including nausea and vomiting and longer intervals may cause liver or kidney damage.
Over 1.0 mg/l (milligram per liter).
In cases where the pH is over 7.0, but the water still causes bluish-green stains and copper levels are still elevated, the source of the corrision is not the pH and raising the pH will generally do nothing. You should cheek and see if everything is grounded properly and make sure that there in not a galvanized to copper connection in the system causing electrolysis. Unfortuneately, in many cases, the source of the problem is not always readily apparent. In that event, the solution is simply to add a polyshosphate injection system. This system is much like an anti-acid for your stomach - it doesn't treat the problem - it simply masks it.