Winterizing Your Portable Restrooms and Handwash Units

When the cold temperatures arrive, so must your determination to protect your assets from the cold. The next series will cover how to winterize everything from your portable restrooms to your specialty trailers so you can keep your investments in good working condition. This post covers winterization tips and brine solutions for even the coldest climate to keep your portable restrooms and handwashing units in great shape. Still, it is up to you to consider the right course of action for the size of your operation, the number of portable toilets in use, the city’s dumping regulations, and the prevailing climate.

Tips and Tricks for Cold Weather Restroom Maintenance

  • Avoid placing the restroom in low areas where snow can melt, collect into water pools, and freeze. Frozen water in a toilet will split the tank, which, in turn, will burst your happiness bubble.
  • Keep restrooms out of windy, exposed areas; placing the restroom next to a chain-linked fence protects it from the wind. It is not unheard of to build a wall to protect your restroom. If a wall or wind barrier is impossible, face the door entrance towards the prevailing wind.
  • Placing the restroom in direct sunlight can help heat the interior on sunny days to keep frost away.
  • Use a winter deodorizer. Cold weather causes regular deodorizers to coagulate. A cold-weather solution like Satellite’s Eco Blue Winter and Quick Blue Winter dissolves and uses effervescent action to disperse throughout the tank.
  • Keep baker’s salt in a coffee can with holes poked through the lid to act as a giant salt shaker for the floor and around the entrance.
  • To keep your brine’s integrity, place a small screen at the base of the urinal. Add water softener pellets on top to ensure the new liquid is not diluting the tank brine.
  • You’ll need a special bio-safe formulation of antifreeze for handwash units. We’ll discuss handwash solutions at the end of the article.

Tank Solutions: Mild Winter Brines

If your climate rarely sees temps below 0 degrees F, you can rely on a salt brine to keep your tanks from freezing. The following are some brine options:

Rock Salt (NaCl) Brine Solution

A rock salt brine solution is the most cost-effective way to prevent your portable restroom from freezing in weather above 0 degrees F. You add more salt as the temperature drops to keep ice from forming. The drawback of this solution is the brine leaves a residue that must be washed away in the spring. All that salt harms nearby plants, trees and flowers, so try and manage your salt levels around gardens and green spaces in case you didn’t know that, like Santa, Mother Nature lists who’s been naughty and nice.

Pros: Cheap

Cons: Limited thaw range, harmful to the environment, leaves residue

Winterize Your Portable Restrooms: Brine (Rock Salt) chart showing rock salt to water ratios.
*2.00 lbs./gallon (NaCl) is the eutectic point. The freezing or protection point will rise with the addition of more than 2.00 lbs./gallon (NaCl).

Magnesium Chloride Crystals (MgCl2)

Sold in solid crystals, similar to rock salt, or as a 30% liquid solution, MgCl2 stays off ice better than regular rock salt (NaCl) at a ratio of 2 lbs. to 1 gallon of water, down to -20 degrees F. Of course, the cost is higher; however, many believe the higher price pays for itself in peace of mind and the extra labor saved by not having to venture out to add more rock salt on freezing cold nights.

Pros: it has a lower eutectic point than rock salt, is less corrosive than rock salt, and is safer for the environment than a similar solution, Calcium Chloride.

Cons: More expensive than rock salt

Winterize Your Portable Restrooms: Magnesium Chloride Crystals and 30% Magnesium Chloride Solution to water ratios.
*2.25 lbs./gallon is the eutectic point. The freezing or protection point will rise with the addition of more than 2.25 lbs./gallons (MgCl2)

Tank Solutions: Extreme Cold Additives


Favored by many because of its non-corrosive attributes to storage tanks, it leaves no residue, and it’s relatively inexpensive. Methanol is effective at temperatures down to -9 degrees F when mixed at its highest ratio before becoming flammable. Methanol being flammable is also its biggest drawback, so when using methanol as an antifreeze solution, be sure to know that there are no fire exposures near, or you could be facing a disaster (lookin’ at you Marlboro Man). You should also check with your city’s waste treatment plant to ensure they accept methanol at their station.

Pros: Not corrosive, no residue, lower freezing rate than salt, inexpensive

Cons: flammable, known toxic properties; not all wastewater treatment facilities accept methanol-treated waste.

Winterize Your Portable Restrooms: Methanol to water ratios.
*Methanol solution becomes flammable when it exceeds 33% by volume, so be very careful not to exceed this percentage

For those who choose to live in the coldest of climates, there is a mix for you! Start with methanol at its highest ratio, 33%. Then, when temperatures drop below -9 degrees F, add rock salt (NaCl) instead of more methanol, which is a fire hazard. A 30% ratio of methanol and 2 lbs. of rock salt/gallon of water will protect your tanks from ice to -40 degrees F. Even the Abominable Snow Man is impressed with that concoction.

Pros: provides freezing points up to -40 F

Cons: harmful to the environment, leaves residue, flammable, known toxic properties. In addition, not all wastewater treatment facilities accept methanol-treated waste.

Winterize Your Portable Restrooms: 33% Methanol plus rock salt and water ratios.

Handwash Sink and Station Winterization

To keep handwash units working in freezing temperatures, or to store your handwash units safely, winterization is a must.  Since hand-sink water has direct contact with human skin, you must use a non-toxic formula. Satellite‚Äôs EZ FlowTM antifreezing concentrate is formulated to be in contact with human skin and yet is effective in keeping sinks ice-free while in use.

To store your handwash units during cold weather months, drain handwash units of water completely and add 1/4 gallon of EZ FlowTM. Cycle EZ FlowTM through the plumping several times to make sure it gets into all of the plumbing, pipes and fittings. Coating the pipes with EZ FlowTM protects them and the fittings from freezing temperatures all winter long until the warm weather returns.

Winterizing your portable restrooms and handwash units in cold weather is a must in the industry. With this information, we hope that this year’s winterization is a warm breeze. In the next post, we discuss winterizing your truck fleet. Stay tuned!

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