You need a tube cutter, a deburring tool, sand cloth, a fitting brush, an acid brush, flux, lead-free solder and a propane or MAPP torch. Add heat-resistant gloves, safety goggles, a flame protector, a fire extinguisher and rags. The fire-safety gear matters as much as the solder.
What goes in the soldering kit?
Oatey, which makes soldering supplies, lists the full kit for a copper job. Here is what each item does.
- Tube cutter. It makes the square cut Oatey's guide calls for.
- Reaming or deburring tool. Many cutters fold one out. It clears the inside edge so burrs do not restrict flow or catch debris.
- Sand cloth or abrasive mesh. You scrub the pipe end bright. Oxidation stops solder from bonding.
- Fitting brush. A wire brush sized to the pipe cleans the inside of the fitting the same way.
- Acid brush. A cheap, stiff brush that spreads a thin coat of flux.
- Flux. It wets the metal and keeps it from oxidizing while it heats. Oatey's guide says "more is not better."
- Solder. Lead-free wire for anything that carries drinking water (more on that below).
- Torch. Propane or MAPP, with a tip that matches the pipe size.
Buy the solder and flux labeled for potable water, not whatever is on the next shelf.
What safety gear do you need?
Oatey's list adds a flame protector, heat-resistant gloves, safety goggles and a fire extinguisher, plus dry and damp rags. Its safety section also suggests a spray bottle of water to dampen nearby materials, long sleeves and closed-toe shoes.
The flame protector is the one people skip. It is a heat shield you put between the joint and the framing, drywall or insulation. Oatey recommends it "especially when working in wall cavities or old homes." Before lighting the torch, scan for paper-backed insulation, wood framing and plastic fixtures. After the last joint, check again for anything smoldering out of sight.
Here's the part that matters in a Phoenix attic or garage: dry framing and old insulation sit right behind most joints. Keep the extinguisher within reach, and never solder directly overhead, because Oatey warns hot solder drips fast. Work from the side and plan your sequence so you never reach across a fresh joint.
Why must the solder be lead-free?
Because federal law says so. EPA states that the Safe Drinking Water Act prohibits the "use of any pipe, any pipe or plumbing fitting or fixture, any solder, or any flux, after June 1986, in the installation or repair of" a public water system or any plumbing "in a residential or non-residential facility providing water for human consumption, that is not lead free." For solder and flux, EPA defines lead free as 0.2% lead or less.
So read the label. Drinking-water pipe gets lead-free solder and water-soluble or tinning flux made for potable systems. Rosin-core solder is for electrical work. Acid-core solder, Oatey notes, is meant for galvanized metal repairs. Oatey points both to other jobs, not to a drinking-water line.
How much solder and which torch tip?
Match the torch tip to the pipe. Oatey says to use a smaller tip for pipe 1 inch and under, and a medium or large tip for bigger pipe. An oversized tip on small pipe can burn off the flux and make the solder fail.
You also need less solder than you think. Oatey's rule of thumb is a length of solder about equal to the pipe diameter: half an inch of solder for half-inch pipe. If the solder melts and drops straight down instead of being pulled into the joint, the pipe probably was not cleaned or fluxed right, or the heat was uneven.
What about the pipe you are repairing?
Tools are half the job. The other half is the setup, and this is where DIY solders go wrong.
- 1Cut and deburr the pipe, then clean both surfaces. Avoid touching them with bare hands because skin oil can hinder solder flow.
- 2Flux a thin coat on the pipe end and inside the fitting. Seat the pipe fully and do not disturb the joint.
- 3Heat the fitting, not the pipe, and touch the solder to the side opposite the flame.
- 4Wipe the joint with a damp rag while it is still hot, then let it cool before turning the water on.
If you are tying into existing lines, our guide to what causes pinhole leaks in copper pipes helps you decide whether the pipe you are cutting into is worth saving. If you wonder whether soldering is even the right method, read press fittings versus solder. New to the pipe itself? Start with copper pipe types K, L and M.
Can you do this yourself in Arizona, and when should you call someone?
Arizona law exempts property owners who improve their own property and do the work themselves, if the structure is for the owner's own occupancy and is not for sale or rent (A.R.S. 32-1121). That covers a homeowner fixing a pipe in a home they live in. Permits are a separate question, so check with your city before replacing more than a repair.
One local rule affects copper outdoors. Phoenix's amendment to the plumbing code says nonmetallic potable water pipe, fittings and valves "shall not be exposed in exterior outdoor locations," so exposed hose-bib and irrigation feeds belong in metal like copper.
Be honest with yourself about the job. A single accessible joint on a stub-out is a reasonable first project. Soldering in a tight wall cavity, near a water heater gas line, or on pipe you cannot fully drain is where the fire and flood risks live. For those, or if a solder joint weeps after two tries, HQ Plumbing and Air is licensed and insured, and we give free estimates with the price up front. For a broader look at the basics, see our list of basic plumbing tools every homeowner should own.