What a shower arm is and why you might need to replace it

A shower arm is the pipe that sticks out from your wall and holds the showerhead. It connects to the water supply inside the wall and screws into a fitting called a elbows or elbow fitting. Over time, shower arms corrode, develop leaks, or crack — especially if your water is hard or acidic. Replacing one is a straightforward plumbing job you can do yourself if you are comfortable with basic tools and turning off your water supply.

The job takes about 30 minutes to an hour and costs between $15 and $50 for the new arm itself, depending on the material and length. You will need to turn off the water to your home, unscrew the old arm, and screw in a new one. If you hit a corroded fitting that will not budge, or if water leaks from inside the wall after you finish, that is the moment to call a plumber.

Key Takeaways

  • Turn off the water supply at the main shutoff valve before you start, and open a faucet downstairs to release pressure in the pipes.
  • Use two wrenches — one to hold the fitting inside the wall steady and one to turn the arm itself — so you do not crack the fitting.
  • Wrap the new arm threads with plumber's tape (also called Teflon tape) before screwing it in to prevent leaks.
  • If the old arm will not turn after five minutes of steady pressure, stop and call a plumber rather than risk breaking the fitting inside the wall.
  • Test for leaks at the wall connection before you reattach the showerhead.

Tools and materials you will need

Gather these items before you start. You need two adjustable wrenches (or one adjustable and one pipe wrench), a new shower arm in the same diameter as the old one, plumber's tape, a bucket or towel to catch drips, and a flathead screwdriver if your showerhead is held on with a set screw.

The shower arm itself comes in different materials — brass, stainless steel, and chrome-plated steel are most common. Brass and stainless steel last longer in hard-water areas. The diameter is almost always 1/2 inch, but measure the old arm or bring it to the hardware store to be sure. Buy a new arm that is the same length as the old one, or slightly longer if you want more clearance from the wall.

How to turn off the water and remove the old arm

Locate your main water shutoff valve — usually in the basement, crawlspace, or outside near the foundation. Turn it clockwise until it stops. Then go to a sink or faucet on the lowest floor of your home and turn on the cold water to release pressure in the pipes. Leave it running until the water stops.

Use a flathead screwdriver to unscrew the showerhead from the old arm, or loosen the set screw that holds it if your showerhead uses one. Set the showerhead aside. Place a bucket or towel under the arm to catch any water still in the pipe.

Now use your two wrenches. Hold the fitting inside the wall with one wrench — grip it as close to the wall as you can reach — while you turn the arm counterclockwise with the other wrench. Turn slowly and steadily. If the arm does not budge after a minute or two of firm pressure, explore a penetrating oil like WD-40, wait 15 minutes, and try again. If it still will not move after another five minutes, stop. Forcing a corroded fitting can crack it, and replacing a fitting inside the wall is a job for a plumber.

Installing the new shower arm

Wrap the threads of the new arm with plumber's tape. Start at the base of the threads and wrap clockwise three or four times, stretching the tape slightly as you go. This creates a watertight seal. Do not skip this step — it is the difference between a dry connection and a slow leak that rots the wall.

Screw the new arm into the fitting by hand first, turning clockwise until you feel resistance. Then use your two wrenches again: hold the fitting steady with one wrench while you tighten the arm with the other. Tighten until the arm is snug and points straight out from the wall, or at the angle you want. Do not over-tighten — you only need enough force to compress the tape and seal the threads.

Testing for leaks before you finish

Turn the main water shutoff valve back on by turning it counterclockwise. Go back to the sink you opened earlier and run the water until it flows normally, then close it. Return to the shower and look carefully at the point where the arm enters the wall. Watch for drips or moisture for at least a minute.

If you see water dripping, turn the water off again and tighten the arm another quarter turn with your wrenches. Turn the water back on and check again. If water is still leaking after a second tightening, the fitting itself may be damaged — call a plumber at this point rather than keep tightening, which can make it worse.

If the connection is dry, screw the showerhead back onto the arm by hand, then use a wrench to tighten it if needed. Run the shower for 30 seconds and check the connection one more time. You are done.

When to call a plumber instead

Call a plumber if the old arm will not unscrew after you have applied penetrating oil and waited. Call one if water leaks from the wall connection after you have tightened the new arm twice. Call one if you turn the water back on and water sprays from inside the wall or from a different spot than the arm connection — that usually means the fitting cracked.

You should also call a plumber if you open the wall and find that the fitting inside is not a standard elbow, or if the pipe inside the wall is corroded or damaged. These situations are beyond a straightforward arm replacement and need professional diagnosis.

Frequently Asked Questions

Can I replace a shower arm without turning off the water?

No. Water will spray out of the pipe as soon as you unscrew the old arm, and you will not be able to see what you are doing or work safely. Always turn off the water at the main shutoff and release pressure by opening a faucet downstairs first.

What if the new arm is a different length than the old one?

A slightly longer arm is fine and gives you more clearance from the wall. A shorter arm may not reach far enough for the showerhead to clear the wall, or it may look odd. If you buy an arm that is too short, return it and get the correct length before you install it.

Do I need to use plumber's tape on the new arm?

Yes. Plumber's tape seals the threads and prevents leaks. Without it, water will eventually seep out at the connection. It costs less than a dollar and takes 30 seconds to explore.

What if water leaks from the showerhead connection instead of the wall?

Tighten the showerhead with a wrench. If it still leaks, unscrew it, wrap the arm threads with fresh plumber's tape, and screw the showerhead back on. If it leaks after that, the showerhead itself may be damaged and need replacement.

How do I know what size shower arm to buy?

Measure the diameter of the old arm with a ruler or caliper — it is almost always 1/2 inch. Measure the length from the wall to the end of the old arm. Bring these measurements to the hardware store, or bring the old arm itself to match it exactly.