Products Filters Parts F.A.Q.s Promotions My Account View Cart
Reverse Osmosis Technlogy Water Education
& Your Health
Customer Reviews
& Testimonials
Talk to a WQA Certified
Water Specialist

How To: Auto-Shut-Off (ASO) Valve Replacement

To replace the Auto-Shut-Off valve on your RO system, please follow steps below:

  1. Turn off the feed water to the RO system. Close the tank’s ball valve. Turn on the RO spigot, lift lever up & lock –> this relieves the pressure in the RO system, making line removal easier.
  2. The ASO valve is mounted on the RO frame. There are 4 ports on the ASO valve, see diagram below. Each port connects to a water line: Two RED lines in ports #1 and #2 (at bottom), two CLEAR lines in ports #3 and #4 (on top).
  3. Take ASO valve out of its bracket.  Please note how the 4 lines are connected to the old ASO, so you can re-connect the lines to the correct ports on the new ASO valve.
    Remove the lines:
    • Disconnect all 4 lines from the old ASO.
    • Each port is a “quick-connect” type fitting. To remove line, press in and hold down on the small “collet” ring around the opening of the port, this will release the line. Pull line out while holding down the collet ring.

    Connect the New ASO:

    • To connect line: simply push line into port (don’t add inserts or Teflon tape).
    • Connect the lower left RED line to port #1 (marked “IN” on ASO).
    • Connect the lower right RED line to port #2, (marked “Out” on ASO).
    • Connect the upper right CLEAR line to port #3, no marking.
    • Connect the upper left CLEAR line to port #4, no marking.
    • After connecting the 4 lines, the ASO side that has the “IN” and “OUT” markings should face down. Mount ASO valve back into bracket.
  4. After ASO replacement, turn on feed water, open the tank valve.  Re-start RO system as usual.

NOTE: If there is no water after replacing the ASO valve, this means the lines did not go to the correct ports. Check and verify all 4 line connections will fix such problem.

If the issue was not addressed, please contact us at:
800-880-4808, or

About Water Quality Specialist

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!

You must be logged in to post a comment.