Solder types used on copper pipes is generally available in three types:
- 50 percent lead/50 percent tin;
- 95 percent tin-antimony/5 percent lead;
- And lead free solder.
Soldering copper pipes used for water supply shall be soldered with product containing no more than 5 percent lead, or instead lead free solder. The 50 percent lead solder is recommended on copper drain lines, because it tends to bridge larger gaps, as the ones you should have on large diameter copper pipes and fittings.