How to Prepare a Restroom Trailer for the Winter Months

Photo courtesy Ameri-Can Engineering

Harsh winter conditions can wreak havoc on restroom trailers, damaging plumbing and batteries. Winterizing units protects your investment. You can check the trailer’s manual for specifications and use this guide to prepare a restroom trailer for the winter.

Drain Water from the Restroom Trailer

The first step involves removing all water from the restroom trailer’s water lines, including traps, pumps, and tanks. Level your unit to assist with drainage and turn off the electricity to the water heater. If your water heater has a drain, empty the tank. Drainless water heaters must be removed and drained.

Then, turn off the water supply valve and open the bypass valve. Click the water pump switch on and open all faucets. You should run the pump until all water has emptied into your wastewater tank. Remember to flush the toilet to release excess liquid. Lastly, drain the wastewater tank.

Blow Out Excess Water with Compressed Air

This optional step forces the remaining water out of the plumbing components. It can reduce the amount of RV antifreeze (propylene glycol) needed but is more time-consuming. Start by attaching a 3/4-inch threaded hose fitting to your air hose and connect the water intake valve to the air compressor. Open the fill valve and turn on the air compressor.

Begin with the fixture furthest away from the air supply. Run sinks and showers until only air escapes. Continually flush toilets and urinals until only air comes out when flushing. It may take two or three rounds to clear the lines completely. After finishing, turn off the air compressor and close the fill valve.

Add Antifreeze

Even if you blow out your lines, water can remain in p-traps or plumbing valves. You will still need to add some antifreeze to prevent damage. If you didn’t use compressed air, all lines must be filled with pure antifreeze.

Run RV antifreeze through the plumbing system using an external 12-volt or onboard water pump. For restroom trailers with onboard pumps, open the outdoor shut-off and city fill valves. Connect the clear hose to the water pump intake and put the other end into a gallon of antifreeze, or if you have an onboard water pump, you can dump antifreeze into your freshwater tank.

Double-check that the water supply to the water heater is shut off and the bypass valve is open. Turn on the pump and start with the furthest fixture by opening the spigot. Run antifreeze through the lines until only antifreeze runs out. Repeat this step for each sink, toilet, shower, and urinal.

Pour 16 ounces of antifreeze into waterless urinals. Confirm that there’s antifreeze in each toilet p-trap. Also, verify that toilet water supply valves and metered faucet cartridges have antifreeze. Finally, ensure each toilet ball valve is closed and put in a few ounces of antifreeze.

Prepare Batteries and the Roof

Remove the battery by disconnecting the negative terminal and then the positive one. Check for corrosion and, if present, remove it by cleaning the battery with a wire brush and baking soda-water mixture. Confirm that the battery is fully charged and has enough liquid.

Inspect the roof for cracked or worn seams. Note any maintenance required, as these are great tasks to keep staff busy during the winter.

Protect Restroom Trailers from Freezing Temps

Companies that run trailers to avoid losing business in the winter can put an antifreeze kit in the units to handle onsite jobs. Otherwise, you can store your restroom trailer and know your investment is protected.

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