It was time to redo the kitchen. When we did the dormer 25 years ago, the plumber ran the copper tubing across the kitchen ceiling and over to new upstairs bathroom. I trusted that copper at the time. After all, the original copper that went to the downstairs bathroom had served the house since 1950 and it was doing just fine.
But as the years went by, that 25-year-old upstairs cold-water copper line developed three leaks in three years and always in the exact same spot. It was a foot or so from the nearest fitting and directly over the kitchen cabinets. The tubing just turned green in the darkness of the joist bay and leaked.