I had my home re-plumbed about 1988 in copper tubing. Type L was used. It has a circ. pump with expansion tank, check valves, and the WH is outside in a shack. Now that I am remodeling, and re-piping again, I am just curious. I had perhaps 20 pin holes develop and leak, mainly at fittings, from then until now. Anyone else have this/know the causation?