Zion Srt grey tanks

[Kevin4404]

Why does Zion Srt shower drain backs up when grey tank at 67%

 

[Kevin4404]

Also, is there a waterless trap or a U drain on the shower drain

 

[Wemustrv]

While I have not seen this I have heard that in some RVs the shower is routed to the black tank so maybe a possibility. Check Blank tank level. Does the water eventually drain or not? Also Tank gauges are known to give false readings.

 

[Kevin4404]

It does drain when I dump grey tank.