Avoid Ice Cube Holding Tanks

A New England PRO working through his first winter wonders how to mix a brine to keep his restrooms from freezing


I’m a first-year PRO in northern New England and am looking at making up a brine solution. What does everyone else use to prevent freeze-ups?


The easiest way I have found to make saltwater brine requires a tank (150-300 gallons), a sump pump, 1 1/2-inch hose, and granular salt (looks like table salt). Fill the tank with water. Hook the hose to the pump. Place the pump in the tank and loop the hose back into the tank so that the water can re-circulate. Turn the pump on and let the water re-circulate, then start adding salt slowly. Here are the salt-to-water ratios for freezing protection: 1/2 lbs/gal. to 26 degrees F; 2 lbs/gal. to 0 degrees F. Let the pump re-circulate for 5-10 minutes. Turn the pump off, hook the hose to the truck, turn the pump on and fill the truck.


We use calcium chloride to make our brine, mixed at 617 pounds of calcium to 480 gallons of water in the coldest time of the year, and adjusted accordingly for warmer times. This will not freeze in -22 F. What we were finding is that urine was diluting the brine solution, and on really cold days, it was causing freezing.

Last year, we started putting rock or road salt into the urinals, so as the user urinates in it, working brine is produced. We didn’t have one unit freeze up last year. Remember if you use the rock salt in the urinal to put something over the hole so all the salt doesn't flow into the holding tank, but still allows the urine to flow through.

Here in Canada, we start with a weaker solution early in the winter and work up to that full strength in the coldest part of winter. If you want to experiment, make your solution and fill a pop bottle with it, then hang it from a tree. If it freezes, you need more salt. Play with different mixes to see what works for your area.

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