black water tank smell

secretcheese3000 wrote:

Lynnmor wrote:
If you leave the gray tank valve open, then any leakage from the air admittance valve will have a full time stink coming from the septic tank.

Can you tell me more about the air admittance valve? I thought the grey and black tanks were unconnected except for being drained from adjacent valves. But now we have a sudden and mysterious black tank smell after six years of full-timing. How does the black tank smell get into a greywater air admittance valve when the grey valve is left open?

We dump 2/3 full and run a Lil Stanker inline vent on the black tank. Weve had zero trouble until the grey valve was left open continuously. I just don't understand how the smell from one system gets into the other system. I thought the dump valve manifold separated the two completely. What am I missing?

If you are leaving your dump hose connected and the gray valve open, your entire gray system can potentially vent the sewer/septic system you’re connected to, not your black tank. If the air admittance valve is leaking, that foul air will enter your RV. Leave the gray valve closed and dump it frequently too or as was suggested create a P-trap in the hose to block the airflow.