I was recently checking the pipes clips in the basement to replace old ones, and when I moved a ceiling tile, I noticed the 2 valves that go up to the kitchen/bathroom sinks - are completely green and almost fuzzy with corrosion. There is no current leak, but at one point there was (I've been in the house for 5years). How bad is this and how quickly should I think about repair? I don't know if it's something that is no sweat or should I get right on it!?! thank you in advance for advice.