old copper pipes should be ok, as any lead solder will have formed a layer of oxidation over it, preventing it from dissolving in the water. galvanized pipes eventually clog with mineral deposits, but are otherwise ok.

the main thing is to know your local water's parameters. call your utility company to see what they treat with, and what the ph is. i have been adding rainwater ph 6 to my filtered tap water ph 7.2 50/50 to get the ph under 7, for small quantities, which i use for budgett frogs and snapping turtles. i do daily complete changes on them.

i still filter my tap water with a brita, but for large quantities, as when i change 20 gals, i have been using tetra's aquasafe. just dump in the correct measured amount, and fill the tank back up with fresh tap water. then you may have to adjust the ph depending on what you are keeping. my acf's seem fine at a ph 7.2, which is how it comes out of the tap, and i do complete water changes once a week on them.