For my plumbing needs, I choose to use 1/2" ID (inside diameter) copper pipe (rigid) and 5/8" OD (outside diameter) copper tubing (flexible) mainly for cost advantages. 1/2" copper pipe is ubiquitous and inexpensive in Dallas, and there are a large variety of fittings available for it. 1/2" ID copper pipe is 5/8" OD, so you can use the 1/2" copperpipe fittings for the 5/8" copper tubing. On all threaded fittings, I used teflon tape as a sealant.

I tried to minimize the use of brass in my system because some brass contains small(<10%) amounts of lead for machinablilty. I did end up using two brass compression fittings, but I used a 2 to 1 ratio solution of vinegar to hydrogen peroxide to remove the surface lead from the brass as originally recommended (I think) by John Palmer in HBD 1539 . For those of you interested in the whole lead in brass subject, I recommend searching the HBD at or at Spencer's Beer Page

Instead of using brass ball valves, I am using nickel plated brass ball valves that hopefully minimizes lead exposure. I hope nickel isn't bad for you. Ideally, I would like to use SS ballvalves, but they run about $30 each. I was able to pick up the nickel plated brass ball valves for about $9.00 each. Regular brass ball valves cost about $6.00 in my area.