Skip to main content


Moen Solutions

What Is A Stacking Leak?

If you are unable to correct the issue after reviewing the following check list, click here for additional information.
Tub and Shower Stacking Leaks
Symptom: When a 1, 2 or 3 handle tub and shower exhibits the annoying symptom of shared flow or STACKING. The consumer turns the water flow on and, instead of the flow immediately coming out the tub spout, they are getting a trickle or more out of the showerhead.
stacking leak.png
This document covers the diagnosis process for a one-handle, two-handle and a three-handle tub and shower faucet. If none of the reasons below apply please contact us for further assistance at 1-800-BUY-MOEN
Single Handle Stacking Checklist
1. Installation Layout: Check that the spacing between main valve and the outlets for the tub spout and showerhead are within the guidelines on the instructions.
  • The tub spout must be installed 6” min and 11”max below the valve.
  • The showerhead outlet must be at least 46” above the valve. Solution: Re-plumb the outlets to the correct spacing

Click here for more details on specifications

2. Piping Material: The Installation Instructions specify that the piping used from the valve down to the tub spout outlet be 1/2” metal pipe (Copper, Galvanized or Brass IPS threaded pipe). Solution: Replace incorrect piping.

Click here for more details on piping materials

3. Tub spout: Remove the tub spout. If the stacking problem goes away, examine the tub spout for restrictions or damage, this could include debris or the white diverter gate in the spout not opening and closing completely. Solution: Clear the restriction and ensure the diverter is pushed all of the way down. If necessary, contact Moen for a replacement tub spout.
4. Multiple elbows between the valve and spout: Only one elbow should be used between the valve and spout. Elbows slow the water down as it exits the spout and could create the stacking symptom. Solution: Remove any additional elbows to leave one elbow between the valve and tub spout.

5. Upside-down valve: If a valve is installed upside down it will send the water to the showerhead first instead of down to the spout. Check your installation and make sure the “up” is facing the ceiling. Solution: Reinstallation of the valve may be required to correct the stacking.

Click here for a picture of what the valve would look like upside-right.

Two-Handle Tub and Shower Stacking Checklist
For two handle tub and shower stacking leaks, follow steps 1-4 for single handle tub and shower stacking checklist. These steps still apply to two handle. Then continue to the step below.

6. Upside-down flow Director: If the valve was mounted upside-down to accommodate water supplies that come in from the ceiling, the flow director must be removed and installed into the side of the valve the water supplies enter. Solution: Remove the flow director and reinstall correctly.

Click here for more details on correct installation of an upside-down installation.

If you are unable to correct the issue after reviewing the following check list, click here for additional information.

 Still Not Finding What You're Looking For?

 Call 1-800-BUY-MOEN           

Non US?  Moen Canada | Other International Sites   

Identify my product icon.png


  • Was this article helpful?