I have a 75 gallon "Drag Up Tank" in the bed of my truck. When completely fueled up I am at 110 gallons on board.
The biggest thing about the transfer tank is I have both sediment and water filters on it.
I have gotten water at a Shell station in FL once. This station is where all of the large diesel vehicles in the small town purchased their diesel. For a year I filled up there every other month. Never had a problem with the water filter stopping up or seeing milky fuel in its sight glass on the previous 5 visits. With this decent track record on my last visit I wanted to only top off the fuel tank. I broke my rule of pumping only fuel from the transfer to the main tank this one time. Well I had water for the first time ever. Very bad luck for me. Lost two injectors and 35 gallons of fuel.
Second time I received water in my fuel was at a national chain truck stop in NM. I never would have bet on their storage tanks having water. I really had to stop for fuel also. Main tank at a 1/4 and I knew I had about 15 gallons in the transfer. Late in the evening and was wanting to rest so, I pulled in to the truck stop for fuel and rest. I was pumping into the transfer tank until the pump read about 20 gallons and then started the pump on the transfer tank. Things were going well for about 3 or 4 minutes and I saw the sight glass turn milky and the nozzle shut off. Filter would not pass fuel. Shut off both pumps. Took a small plastic bottle and drained the sight bowl. Let it stand for a minute or so and of the 8 to 9 oz of liquid in the bottle more than half was water.
I went in and showed the night supervisor. She said they were low and that the delivery truck normally showed around 11 pm. I have not stopped at that chain anywhere since. No concern about my situation. BTW- I was at the RV Island.
I enjoy being able to fuel up at the rest areas. I can do that, get out and walk, go to the restroom, walk down the truck and 5th wheel at leisure. I am not holding anyone up and I find I top off at half a tank because that is about 4 hours of sitting and driving. Time to move around.