Installing a Water Supply System

Most Common Mistakes

  • Violating or ignoring code restrictions.
  • Using supply pipes that are too small.
  • Moving or knocking copper pipes while the newly sweated fittings are still hot.
  • Creating fire hazards by leaving materials smoldering after sweating fittings.
  • Attaching copper to galvanized without using a brass or dielectric fitting between the two.
  • Not using PTFE tape or pipe compound at threaded pipe joints.
  • Not running pipes to correct locations.
  • Trying to solder a pipe joint when the water has not been completely drained. (Be certain the main valve is turned off and that the supply lines are drained at the lowest point of the house, at the tub/shower and at the sinks. Flush all toilets.)

  • If you drain the lines at the outside hose valve, this is best. Just be sure this valve is fed from the house main rather than from the well or city water main.
  • When turning the water back on in your home, always run the outside hose valve or flush your toilets to bleed dirt and air from the lines. This debris can cause problems in your sink faucets and other plumbing trim.

Joining Copper Pipe

You will need to purchase your copper fittings in accordance with the joining method you will be using. Soldering is the method used to join hard copper pipes together. For this you will require a small butane or propane torch, 00 steel wool or emery cloth, a wire pipe brush, a can of soldering flux and some solid core wire solder. Check you local code for the wire solder required in your area. Some require 50/50, which is 50 percent tin and 50 percent lead, and is stronger than 60/40 for a better joint connection. Others use lead free.

Measuring and Cutting Copper Pipe

To determine the length of copper pipe, you will need to measure the distance between the fittings and add the distance the pipe will extend into each fitting. Keep in mind that pipe insert distances will vary for various types of joints. Although usually 1/2" pipe will insert 1/2" and a 3/4" pipe inserts 3/4". Copper pipe can be cut with a pipe cutter that has a blade designed for cutting copper. Use the cutter by placing the pipe into the opening and twist the knob until the cutting wheel just pierces the copper pipe. Then rotate the cutter around the pipe, tightening the knob after each revolution, until the pipe snaps in two. After you have cut the pipe, use the special blade on the tubing cutter to ream out the "burr" on the inside of the newly cut pipe.

Tip: Whether using hard or soft copper tubing, take care not to damage it as you work. Cover the jaws of wrenches or vices with electrician's tape.


1. Drain the pipes completely, because any water in the pipes will interfere with a successful soldering job. Turn off the main water supply valve and open a faucet at the low end of the pipes. Usually an outside hose bibb works best.

Hint. Once the water has drained out, stuff some plain white bread into the pipe near the fitting you are about to solder to absorb any remaining moisture. Once you turn the water on again, the bread will disintegrate.

2. Use the steel wool, emery cloth or very fine sandpaper to polish the last inch of the outside of the pipe and the inside of the fitting down to the shoulder. Wire pipe brushes, which clean both the outside of the pipe and the inside of the fittings, are also available in both 1/2 and 3/4 inch sizes. It is important that you clean both fitting and pipe thoroughly. Time spent on this step will save time later fixing leaking joints. It is much easier to do it right the first time.

3. Apply flux around the polished inside of the fitting and around the polished outside of the pipe end. (Some solders are available that contain the flux within the solder.)

4. Place the fitting on the pipe, twisting back and forth a couple of times to assure even distribution of the flux.

5. Heat the bottom of the pipe first with the propane torch. Slowly pass the torch back and forth across the fitting to distribute the heat evenly. Take care not to get the fitting too hot because the flux will burn away to nothing. You can tell the joint is hot enough when the soldering wire will melt easily on contact with it and not stick. By touching the soldering wire to the joint occasionally as you heat it, you can avoid overheating. The moment the wire melts, the joint is ready.

6. Remove the torch and touch the soldering wire to the edge of the fitting. The solder should pull in between the fitting and the pipe by capillary action. Continue to solder until a line of molten solder shows all the way around the fitting. Be certain there are no air gaps between the solder and the pipe fitting.

7. Wipe off the excess surface solder with a damp rag before it solidifies, leaving a trace of solder showing in the crevice between fitting and pipe.

Caution: Keep your hands well away from the hot joint and take care not to bump or move the newly soldered joint until it has cooled.

Air Chambers or Cushions

Often pipes will bang when a faucet or valve is suddenly cut off. This can damage the pipe and is irritating to live with. The banging is caused because water does not compress when its flow is suddenly stopped. To prevent this, we recommend installing manufactured air chambers, or shock absorbers, into the hot and cold supply lines at each fixture. These contain inert gas and bellows that absorb the shock. These manufactured products work better than using a one foot length of copper pipe as these must be drained every
few years. These fittings may need
to be replaced or have parts within them replaced
on a regular schedule.