Forum Discussion

RWjSIM2003's avatar
RWjSIM2003
Explorer
Oct 25, 2014

CHECK VALVE ISSUE?

I have small amounts of water under the bathroom sink checked all connections and drain pipes. could not find any leaks cleaned and dried area. next morning I see what looks like condensation on the drain pipe from the vent check valve down and bottom of cabinet is damp. Anyone had this issue? I have no sewer gas smell like the valve is bad. I am stumped
Class A

3 Replies

  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Oct 25, 2014
    Black tank flush anti-siphon valve (some are clear or brass)



    Air Admittance Valve on sink drain line (can be white/different style)



    Neither should be dripping.....
  • RWjSIM2003's avatar
    RWjSIM2003
    Explorer
    Oct 25, 2014
    Found the issue after sitting and watching for 30 mins I could see that the hot water line would drip every so offen and it was right above the Vent Check valve. Cleaned added Teflon tape to connector and no more leak. Life is good until the next issue !!!!
  • Bill___Kate's avatar
    Bill___Kate
    Explorer
    Oct 25, 2014
    If it a a vent valve on the sink drain line, it is possible that the little diaphram sometimes doesn't seat properly. It is easy to unscrew it, take it out and inspect it.

    If you have a built in black tank flush, there is often a check valve - vacuum breaker installed on the water inlet under the bathroom sink. These are notoriously troublesome - cheaply made, and prone to leakage. If you have one of those, it can be replaced with a similar valve, better valve, or eliminated.

About Motorhome Group

38,736 PostsLatest Activity: Jul 19, 2025