What Type of Solder Meets Codes for Copper Water Piping?

Acceptable Solders for Residential Plumbing

• The type of solders that meet codes for residential water supply are explicitly labeled "lead-free." Lead-free solders typically consist of a mixture of tin and antimony or silver. Solder alloys that contain silver might cost more than mixtures with antimony, bismuth or copper. Although prohibited for potable water supply piping, leaded solder does exist on retail and commercial markets. Appropriate applications of leaded solder including metalworking and drainpipe welding.

Lead-Free Soldering Tools and Supplies

• The tools and supplies for joining copper water piping with lead-free solder are the same as those used for joining pipes with leaded solder. Plumbers prepare copper pipes and fittings for soldering by abrading them with wire brushes or a material that resembles sandpaper called emery cloth. Plumbers use a paste-like compound called flux to clean and prepare pipes and fitting for soldering. Plumbers typically heat the copper pipes and fittings with handheld torches to activate the flux and to melt the solder. A handheld torch consists of a gas fuel canister and a removable torch tip.

Soldering Copper Pipes

• Before soldering copper pipes, plumbers "sand" or abrade impurities and corrosion from the pipes and fittings until bare copper shines. After coating the separate components with flux, plumbers join the pieces and heat the intersection between pipe and fitting with a torch. Plumbers test the copper's temperature by pressing solder against the joint. If the solder melts into beads and falls from the pipe's surface, the joint isn't hot enough for soldering. If solder melts and seemingly "sucks" into the joint, plumbers continue pressing the solder into the joint until it is full.

Soldering Alternatives

• Alternatives to soldering include threaded fittings, compression fittings and push-fit fittings. Installing threaded fittings onto smooth-ended copper pipes requires soldering at least one threaded adapter onto a pipe's end. On the other hand, compression and push-fit fittings attach to smooth-ended pipe without soldering. Consult your local building authority to determine if soldering alternatives are acceptable for your project.