Thanks for all the thought you have put into this for me. I recorded the sound, but have been able to get it downloaded to the forum. The sound comes with the shore power hooked up, but with no water hookup, I haven't been using a pressure reduction value, but have one on order. The propane gas is off. Water heater, refraig, ac/heaters, and water pumps are all off and I still get the noise.
The sound is different then when the sewer valves are opening/closing, but I will check to assure they are closing all the way, thanks for the idea. l have spent a lot of time trying to track it down and while you can hear the sound anywhere in the rv and outside the rv, it seems to be coming from around the bathroom cabinet.
On a another note my xanteck 1800 inverter makes a beeping noise every second and has a e5 trouble code, which I understand is a overload on the output side. This issue didn't started before the woo sound, but could they be related. Thanks for the continued support. It's tough being the new guy. Thanks Rick