Restroom trailers in winter: what keeps them from freezing during a December wedding?

Keep cabin heat and heat tape powered the whole night, and wrap every exposed connector. That cold spot at a fitting is where freeze-ups almost always start.

On a restroom trailer in the mid-20s, intermittent power is what bites you. Stall heaters keep the interior livable, but the fresh line and hose joints sit outside that warm pocket. I run the generator continuous whenever overnight lows sit near or below freezing, so heat tape and interior heat stay on. Cycling the generator off to save fuel is how you wake up to a frozen coupler.

Do not dose the fresh tank with RV antifreeze while guests are using the unit. Non-toxic antifreeze is for drain-and-store winterization, not for handwashing water during an event. For live service, heat the water path: heated hose from the spigot, heat tape on metal fittings, insulation over the tape, and no bare connector left in wind.

Gray water is the other sleeper. A full tank in a cold snap freezes at the valve and outlet first. I keep the gray side emptied closer to the end of the night when temps drop hard, and I leave the tank area warmer if the trailer package has a bay heater. Your hairdryer thaw worked because the freeze was local. Next time, treat every hose joint as a freeze point before you leave the site.