Our heater was leaking on our last big trip. The check valve they use is plastic. It was almost completely deteriorated and when I went to slightly tighten it the valve crumbled. Fortunately my wife was ready to turn off the water.

I pulled the heater which required me to cut and then later attach the 12v wires because they didn't leave me enough wire to pull the tank out with them attached.

I changed both input and output valves to brass, didn't bother with another plastic check valve which was all they had at home depot that would fit, no issues now.