"Paul J" wrote
I am ready and about to buy materials for the repiping from galvanized
1/2" to copper ?", but what size to use? I would like to go with 1/2"
type K but that takes up more inside diameter then M and L. Should I
go with 5/8" K, 3/4" K or just not be worried about the inside
diameter because it is a very small difference? Then again the
galvanized pipe probably has only an 1/8" openning anyway from all the
years of crap in it.

The best way to determine this is to count up the max gpm of each fixture
and find the flow rate of the pipe based on the pressure you have.

The best material to use should be dictated by your water quality now and
what it might be in the future. There's something in your water now that has
caused the galvanized to rust; will it likewise cause copper to be added to
your water while eating the new tubing? Very probably if you were to learn
about all the things found in water that deteriorates copper tubing. IMO
copper should not be used with a pH of less than 7.0 and then the DO, CO2
and TDS content should not be more than minimal. Electrical grounding and
bacteria are causes of pinholes in copper tubing also, among other things
things. PEX is probably the best material for replumbing water lines bar
none. Copper does not meet the NSF Standard 61 if the pH of the water will
be less than 6.5. The acceptable pH used to be 6.9 to 8.5 but was lowered in
1990-'91 to get water companies to accept the Lead and Copper Rules.

Gary
Quality Water Associates
www.qualitywaterassociates.com
Bulletin Board www.qualitywaterassociates.com/phpBB2/