I have been replacing Cu with PEX and what I was really surprised to note is that the pipes in my place have some pretty nasty residue. I noted clear signs of oxidation / rust (greenish / redish deposit on the inside). Always thought Copper to be very inert metal and though that pipes on the inside stay relatively "like new" IS this a indication that my water is particularly "harsh" or is that normal to notice with pipes from 1950s ? Thanks! PS: All the appliances, water outlets, heating units etc.. always look good and the only issue I have with my water is mild hardness.... visible on crystal and glass after washing in a dishwasher (if not using Jet Dry).

1. I am trying to attach to pieces of drain pipe together, but there is a slow drip coming from the line that doesn't seem to want to stop. I wad up some toilet paper to try and slow it down long enough so I can apply the glue and join but it seems to drip a couple drops on the glue before I join them. Am I at risk of the glue not setting properly or should I be fine as long as I let it setup for awhile? 2. I noticed when re-doing some drains in the house, that the original plumber over 20 years ago used Fernco fittings (the standard rubber coupler with 1 band clamp on each end) on the horizontal 3" drain pipe from my second floor washroom. He used it on 2 locations. Not sure if he had a leak at one point and decided to use this as a fix or what. Now it hasn't leaked in all this time but I'm wondering because I am fixing up some of the plumbing if I should do do this portion or just leave it. I'm not sure what the code for those Fernco fittings is in Ontario Canada. thanks