How To Make Water Tight Connections with Brass Fittings

There are many different materials used for water lines in homes across the country. This will explain one common method for repairing copper water lines.

One of the more common fittings used in copper water line repair is the brass compression fitting. You can find them in most hardware stores across the country as well as home centers.

Brass compression fittings can be tricky to install correctly so they don’t leak.

One of the first considerations is to buy the correct size fitting for the copper water line you are going to repair. Nominal 1/2″ copper is actually 5/8″ in outside diameter. 3/4″ copper is actually 7/8″ in outside diameter and so forth for other sizes of copper pipe. Take care to correctly identify the type of copper pipe you are going to repair. Refrigeration tubing is found on occasion in and under homes and it’s dimensions are different than standard copper water piping so, if in doubt, measure the outside wall diameter with a set of calipers. If no calipers are available, and you have the cut end of the pipe at hand, measure across it with a ruler. In any event, buy 5/8″ brass compression fittings for 1/2′ copper pipe, 7/8″ fittings for 3/4″ copper and so on.

Make certain to cut the copper pipe square with a good tubing cutter and eliminate any burrs from the outside of the copper tubing with a file, sandpaper, emery cloth, or even the dull edge of a knife.

Use brass compression fittings make successful copper water line repairs

Slide the brass compression nut from the fitting on to the end of the copper tube. Now slide the compression ferrule over the end of the pipe and insert the end of the pipe into the brass compression fitting.

Most people, including many professionals, next wrap the threads of the compression fitting with Teflon tape. This is a big mistake. The Teflon tape will actually prevent the compression nut from tightening the ferrule up inside the fitting all the way and cause a leak. Not what you want!

Another agent that people might be tempted to use on the threads is pipe joint compound of one sort or another, also called, in the trade, pipe dope. This won’t work either. In fact, some types of pipe joint compound will actually cause the brass to fatigue and crack. The problem arises in that the crack doesn’t always happen right away. You may think you successfully repaired the joint, only to discover it leaking again a few hours or days later.

To make a leak-free joint the first time around, lubricate the threads of the brass compression fitting with a small amount of lubricant. I especially recommend food grade silicone grease because the water line may be potable. In a pinch, you can use a small amount of WD-40, 3-in-1 oil, Vaseline, or even a liquid soap like dish detergent. It is best to only use the petroleum-based products or soap on non-potable water lines.

Start the nut on the threads and screw it down finger tight. Make sure the pipe is still inserted in the fitting straight; that is very important. Then use two wrenches to tighten the nut up. Hold the fitting with one wrench so the fitting doesn’t turn and tighten the nut with the other wrench. Use two adjustable wrenches or open end wrenches, not pipe wrenches, or water pump pliers because they can damage the fitting. Turn the water on and look at the fitting with a good light. If it leaks a little bit or weeps, using both wrenches, tighten it up a little more. If that doesn’t stop the leak, turn the water back off, loosen the nut a little, straighten the pipe so it goes into the brass compression fitting straight, retighten the nut, and turn the water back on.

Congratulations! You have completed a fast, easy, and inexpensive copper water line repair and have the tools and knowledge to fix any copper water line leaks that may occur in the future.brass compression fittings make successful copper water line repairs.