Missing 20 gallon capacity in my fresh water tank - any ideas?
Head scratcher here. We bought a used 2020 Durango D321RKT fifth wheel last summer (private sale) but only had a chance to use it for 3 days before storing it for the winter. I know I filled the fresh tank until the over flow vents started dropping water and figured it was full. the digital screen in the trailer doesn't track tank levels well, but even in the days with the LED lights or level indicators - tank levels were a bit of a guess. But we ran out of water Saturday night on our first trip and just chocked it up as I might not have been level or some air bubble affected it. This was last October '25 and then we winterized it and been in storage since.
Pic of the Nautilus set up to siphon from my clean bucket
Now it's a new season, I filled it on Saturday to prep for some up coming trips and could only get 35 gallons in and the vent tubes were spilling water again. It's rated for 55 gallons. I did run the pump once it was "full" and filled the 12 gallon water heater and then put in more water, but once again, I'm missing about 20 gallons of capacity. Thoughts?
Some say the vent tubes might be mounted too low on the side of the tank - but it's up inside and enclosed and I'm not wanting to dig around and open that part of the bottom of the trailer up, at least until I have no other choice. Trailer specs say 67 gallons of fresh water (55 in the tank and 12 in the water heater). I called the local dealer that the original owner bought it from and they've done some work on it - they didn't have a lot of great ideas. He said the tank might be "sagging" and need a way to "burp" it to get more water in there - but I don't want to stopper the vent tubes and force more water in there and have it coming back up inside the trailer or drains either or causing issues with the trailer. I'm pretty stumped. it has a Nautilus P4 water management system that I think is more fancy than functional, miss the old days of putting a hose down a side tube to the water tank and a vent hole that spills out when it's full. The original owner never dry camped and lived in it at an RV park for 2 years and kept it really clean on the inside - but dumb as rocks for anything else with the trailer - hasn't been pulled more than 200 miles - seemed too "good to pass up" when we saw it listed in town.
I set it to use siphon and had a clean 6 gallon bucket that I counted the times I had to fill it to then measure the water - digital flow meter coming this week. so it wasn't even filling that fast either. We love to dry camp and would really like to get access to all of the water capacity w/o having to replace the tank and labor costs to go with it.
Vent tubes dropping water around 35 gallons - rig was dead level.
