This turned out to be kind of bizarre. There was an extremely slow seep from one of the kitchen sink shutoffs. Fair enough, the house is 40 years old, and it dates to when it was built. But it was one of those crappy gate-valve shutoffs, which I hate - they always leak, eventually - spend a few extra bucks and get ball valves. But no new-housing contractor is going to pay *anything* extra, just eats into the profit from the job bid...

It was seeping from the valve ... stem? Shaft? Dunno what to call it - the threaded rod that moves the gate open and closed when you turn the handle. It was seeping like a drop every few minutes, through the packing around that stem.

With the cabinet doors open, there was enough air circulation that it never accumulated anywhere - we're a dry climate, and evaporation took care of it. With the cabinet doors shut, drops would occasionally run down the pipe to the cabinet floor.

#ItWorksWhenYoureLooking #plumbing #heisenbug #HomeImprovement #DIY