Pin-Hole Leaks In Copper Plumbing
A pin-hole leak is defined as, "the perforation of copper tube, pipe or fittings used for domestic water distribution as the result of pitting corrosion initiated on the interior/waterside surface with the subsequent leakage of water."
Pin-hole leaks in copper plumbing.
I see pin-hole leaking often. Most often I see it on houses with well water.
While such leaking is not on every joint, it seems to me that I am seeing it more and more lately.
Sometimes the very small leak will seal itself with the minerals that are in the water. But that is no
guarantee that the leak has stopped. Often with that a white or blue-green buildup can be seen at the leak point. That is from metal ions leaching into the water - iron, copper, manganese, lead, etc. These minerals exiting the pit hole can build up and actually seal the leak.
The leak can start again at any time, as can be seen on the photo to the left. The yellow arrow shows a drip that was happening there.
Pin-hole leaking is caused by water chemistry or changes in water chemistry. It happens at copper joints and also where brass is used at joints and valves.
Copper has been used in plumbing for many decades, and mostly in the last 50 years or so. Brass has been used in valves and joints because it has little to no galvanic reaction with the copper. See my blog by clicking on the orange link.
There have been other substitutes, but so far none has proved as reliable as copper.
A pin-hole leak is defined as, "the perforation of copper tube, pipe or fittings used for domestic water distribution as the result of pitting corrosion initiated on the interior/waterside surface with the subsequent leakage of water."
Corrosive pitting is the primary cause of leaking in pipes. Pit corrosion happens most often at joints.
The water in both of the houses in the photos was well water.
The chemistry there seems to have been aggressive toward the copper plumbing.
On both houses there was water treatment equipment present in the house.
While the home inspector cannot tell why such equipment may be present in a house, obviously someone at some time had a water test and found the water to be hard, acidic, full of iron, etc.
Acidic water would be defined as having a pH (potential hydrogen) of less than 7. With 7 being neutral, acid is on the lower side of 7, and alkaline on the higher.
Acid in the water chemistry are usually thought to be the primary cause of such corrosion or perforation. But that may not always be the case. But pin-hole leaking studies have shown pit corrosion to happen with hard water with a high pH, soft water with a lower pH, and cold soft water with a high pH. Very low pH however, with a pH of less than 6.5, seems to be the most corrosive.
So houses on well water, with treatment (so-called softening) equipment which removes minerals from the water, and with a lower pH, may be the most vulnerable to pin-hole leaks.
My recommendation: certainly with well water you want a whole-house filter to remove silt and sand and grit from the water. But beyond that, water should be tested for acidity in addition to hard minerals. With acidic water it may be wise not to treat the water for hardness, if copper plumbing is in the house.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
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