How to solder copper water line

If you live in a house built at any time past World War II…about 1946 or so… it most likely has copper water lines in it.  Some newer homes may have PVC water lines.  This is a white plastic, which I will discuss later, this is concerning the copper lines most homes are typically equipped with.  Knowing how to repair the water lines, and having the proper tools and materials to do so is a good thing to have in an emergency.  It is also good to know if you choose to upgrade or make changes to your water lines. You may have seen me soldering copper pipe in some of the other projects I have mentioned on here like the Tankless water heater install Materials and tools: IMG_4867

The following image shows the items you will need to solder copper pipe:

Propane torch:  This is a click to ignite torch.  Obviously, you need a source of heat to melt the solder, and this is it.  These run about $30 or so at any hardware or home improvement big-box store like Lowe’s or Home Depot.

Pipe cutter:  On the far left, the little gray thing is a pipe cutter.  It will be needed to cut the copper pipe to the length you need when fitting the pipes together. While a hacksaw can be used to cut the copper pipe, frequently , and uneven, cut is made, and the pipe is bent, causing the fitting not to go on properly.  A pipe cutter saves a lot of headache in making the pipes fit, and it makes a much more professional cut.

Soldering Paste: Left of center in the red and white plastic cup.  This paste is applied to the fittings and the pipe you wish to solder to make the melted solder flow smoothly into the joint.

Soldering wire: The blue and black roll right of center. The soft metal used to hold the pipes together.  It is important to use lead-free solder on pipes that could contain drinking water.  For pipes that may be used for heating system, you can use 50/50 solder with lead in it.  This melts at a lower temperature and is sometimes better when soldering heat-sensitive valves and other components in a heating system.

sandpaper:  Far right.  Used to clean the oxides off the pipes and fittings prior to joining the pipes together. The bottom row of supplies is typically found all together in a “pipe soldering kit” at most hardware stores, usually around $15 – $20 Okay, let’s get started.  I am going to assume at this point that the pipes are cut to the length of whatever you need them for (using the pipe cutter) and you are ready to assemble.  See my next post on repairing a pipe for how to repair a pipe for assembly instructions.  I am also assuming the water is already OFF too, as you don’t want to be cutting into pipes full of pressurized water!!!

1:  sand the pipe and the fitting.


The first step is to sand the pipe you wish to join together, and the mating surface of the fitting down to remove all oxides.  You should have bright, gold copper showing all over the pipe, and on the inside of the fitting.

2: Add paste


Some of the soldering kits have fancy little brushes if you don’t want to get the stuff on your fingers, but it washes off easily, and it’s safe (it’s going on a pipe you will be drinking water out of!) The most important thing is that the stuff gets all over the pipe.

3: Install the fitting and heat it up!


Now, fire up your torch, and heat the pipe up.  You want to position the bright blue portion of the torch’s flame on the pipe, this is the hottest point.  You want to heat the pipe up quickly and use only as much heat as needed.

4:  Add solder:


When the pipe is hot enough, the solder will melt when it comes in contact with the pipe….this is what you want.  Don’t melt the solder in the flame of the torch, let the hot pipe do it.  Run the solder all the way around the joint between the fitting and the pipe and make sure it flows into it.  Add a little more heat with the torch as necessary.

5:  Allow to cool, inspect, and turn water back on! IMG_4880

This is what it should look like when it’s done.  Now, some experienced plumbers might say this looks a bit sloppy, and yes, it may….I forgot to pull the bar code sticker off the fitting, and it got a little bit too hot and burned the flux.  Not too big a deal.  If you want to, after it cools, you can use a sponge and clean up the burnt.  The important thing is that you have a nice “bead” of solder all the way around the joint between the pipe and the fitting.  The entire gap between the fitting should be filled solidly with solder. …now, turn the water back on and inspect it for leaks!!!

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One Response to How to solder copper water line

  1. Pingback: How to repair a damaged water line | Audvidgeek's Blog

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