help with pin holes??

Hi all. I have been in the wholesale business for around 11 years now, 5 years or so in the field of water treatment. Normally analysis and treatment are straight forward, but I just ran into a problem beyond my experience and need some help.
The homeowner has been living in a 17 year old house for the last 11 years. In that time he has had 5 pin hole leaks, all on the cold water lines, but scattered through out the house (all behind walls). His plumber took the water to a locale lab where they had the following results:

pH 7.0
Calcium/hardness 84 mg/L
Alkalinity 84 mg/L
TDS 175 mg/L
corrosivity -0.85

These results are unusual for our area in that we mostly have pH levels between 6.5 to 6.9 and hardness typically runs between 8gpg and 18gpg.
I suppose the pH could dip with the low alkalinity, but since I never ran into this situation I can not determine if that explanation is reasonable. Another though I had was electrolysis, but I have no practical knowledge on the subject. Any suggestions, info, or similar experiences would be much appreciated.

PH of 7.0 is neutral...not acidic or basic...exactly in the middle.

Electrolysis happens with different metals when they are toughing one another.

Is it copper pipe this is happening to?

bob...

Valveman

Had this problem once long ago. Copper pipe in NEW house, pin holes everywhere. Turned out to be the water heater. If I remember right it was badly grounded, had a shorted element, or both.

You may want the do the pH test on site, otherwise there may be an error; especially if there was air in the sample bottle. That can give a false high result.

There are many causes of pin hole leaks in copper tubing. They range from low pH acidic water to, many types of bacteria, high DO, CO2, TDS, chlorides, content and poor/missing building grounds and grounding electrical equipment to the water lines but, the most common cause is excessive soldering flux; whether water soluble or not. Erosion (gouging out) corrision can also cause pin hole leaks and the most common cause is not reaming the end of the tubing after cutting it. That is especially found in hot water recirculation systems.

A web search for "pin holes" + copper (with the "") will bring up many hits.

I wanted to thank everyone for the suggestions; I hate not knowing why problems occur, even if I can't resolve them personally. Working behind a counter all day, I rarely have the opportunity to view these situations personally and have to rely on 2nd and 3rd hand observations. It really helps to have a place where knowledgeable and experienced people can give direction. Thanks again.