Storage Tank Warmers

There aren't any on any rPod I've ever head of, unless someone added them. And you really shouldn't. They won't protect the water lines themselves, which are more vulnerable to freezing than the tanks, and they use a huge amount of electricity. Its better just to winterize the the trailer when it gets below freezing and use bottled water kept warm in the trailer to flush the toilet and for cooking if you plan on doing any winter camping. 

Lots of threads on here about winterizing, with detailed instructions. If you did a poll of the forum you would finds some folks blow the lines out with compressed air (being careful not to use much pressure) and just put antifreeze in the drain traps, others drain and then pump RV antifreeze into the lines using the provided suction line to the 12V water pump.  Either way you drain the water heater tank, bypass it, and drain all three storage tanks. No major problems I've heard of doing it either way, but if you pump RV antifreeze in you have to flush it out in the spring.