Winter 2026: will porta potties freeze on a Montana construction site?

Yes, a standard portable toilet will freeze solid in Montana winter temperatures. The deodorizer solution, even with antifreeze additives, turns to slush below 20°F and can freeze the entire holding tank solid by 0°F. Your setup has three units for 45 workers, which meets the OSHA 1926.51 minimum of one toilet per 40 workers. The ADA-compliant unit has a larger holding tank but uses the same antifreeze solution and faces the same freeze risk. You need to contact your rental company immediately for winterization. They should add a brine or non-toxic antifreeze solution rated for lower temperatures during the next service visit. Do not attempt to thaw units yourself; cracked tanks are common when people use heaters or pour hot water. Expect a more frequent service schedule in deep cold, possibly twice a week, to prevent complete freeze-ups and ensure the units remain usable. The rental company may charge more for the extra service trips and winter-grade chemicals.

Slush in the tank at 10°F is your warning sign, and a standard unit can freeze into a solid block if nobody changes the mix before January. Our parks crew keeps a few units out at trailheads all winter, and we learned most of this the hard way.

Call the rental office now and tell them exactly what you saw. Ask that the tech recharges the tank with their winter mix on every visit, not just the first one, because every pump out resets it. The ADA unit is the same story with more liquid to freeze, so make sure it gets the same treatment.

Placement helped more than I expected. Turn the doors away from the wind and put the cluster where it catches sun most of the day. Keep the doors latched overnight so snow doesn't drift inside.

Watch the handwash station too. Ours freeze before the toilets do. Where we keep one, we drain it at quitting time and refill it each morning with water stored somewhere heated.

And no space heaters or hot water down the hole. Somebody on your crew will try it.