Hey Doc! The attached photo shows two tubes sticking down from the enclosed bottom of our travel trailer near the black and gray holding tanks. Do you know what they are for? This is an '06 travel trailer. Jack and Nadyne H.
Those two tubes are the low point drains for both the hot and cold water lines in the fresh water distribution system. The code for RV construction mandates each side of the fresh tubing (hot and cold), must have valves, plugs or caps, at the purported lowest point in the system for ease of emptying the system for winterizing purposes. In your case, you have simple caps that can be removed to empty the hot and cold lines in the trailer. It’s also handy for flushing out and chlorinating the fresh water system. They are not relative to the holding tanks; their proximity notwithstanding.
##RVT784