Freezing weather doesn’t stop the need for portable toilets, but when temperatures dip below 32 degrees it does mean that your porta potty is at risk of freezing. This isn’t all that bad. You can still go the the bathroom in a porta potty with a frozen waste tank.  Nothing prevents you from using a portable toilet that has its waste tank frozen over, it’s certainly not ideal, but you can absolutely go to the bathroom if you need to. If the forecast calls for an extended number of days of freezing temperatures it will prevent our Green Latrine portable toilet service trucks from pumping the waste out of your portable toilet. We can not pump ice! If you need you toilet pumped then it is important to take steps to winterize your portable toilets to ensure that they are still usable during the cold periods of our Western WA winter.

Luckily Western Washington winters aren’t all that harsh. Compared to many Midwest and Northern climates Puget Sound fares far warmer wintertime temperatures. But Seattle area winter weather patterns can be cold. From Halloween in late October through to St. Pats Day in March we can certainly have freezer like nights. Frozen porta potties are tough! Impossible to empty the waste from a portable toilet tank when it’s frozen solid. Especially challenging can be keeping toilets from freezing at altitude. Up in higher elevations of eastern King, Pierce and Snohomish Counties and up in the Cascade Mountains at places like Stevens Pass, Snoqualmie Pass or Crystal Mountain keeping toilets from freezing in winter can be challenging. Increased elevation decreases air temperature and increases the chance of a frozen porta potty.

portable toilet help in the snow

Outside Restrooms in the Seattle Winter

As we have addressed, the call of nature doesn’t stop when the Seattle temperature drops. So, if you require regular cleaning, pumping, or service of your temporary toilet it is important to prevent the freezing of portable toilets so that Green Latrine can pump the liquid waste – because we can not pump frozen waste – and these 6 methods below of freezing prevention can do the trick in many cases. Just consider the temperature, location of your portable toilet and the money you are willing to spend, and any of these methods below can work in some cases.

How to Prevent Porta Potties from Freezing – Six Methods To Prevent Freezing Portable Toilet Waste Tanks 

Honestly we really don’t need to do any of this in Seattle or Western Washington. Our winters just aren’t harsh enough. Sub freezing temperatures rarely last for more than a few days. Temperatures rarely get down into the low 20’s or teens where a hard freeze happens BUT just in case you’re interested here is how Portable Restroom Operators in much colder climates continue operating through persistent cold weather.  There are six common techniques you can use to prevent portable toilets from becoming frozen. These different methods come with a lot of different pros and cons, as well as resistance to freezing.

Rock Salt

Rock salt is definitely the most affordable solution to prevent freezing during the winter months. However, this is only a good choice if the winter months in your region do not regularly bring the temperature down below 0°F.

Rock salt can be applied in varying amounts, and the more you add, the greater the protection it will add up to the rock salt’s eutectic point, which is at about 2 lbs of salt for every gallon of water. At this point, the portable toilet waste tank will not freeze unless the temperature drops below 0°F.

Magnesium Chloride

MGCI2 de-icing solution is one of the most common options to prevent portable toilet freezing. This additive can be added as a crystal or a 30% liquid. Though this method is far more costly than rock salt, it is far more effective to prevent porta pottys from freezing in winter.

Mixing MGCI2 crystals into every gallon of water will offer protection down to -26°F. This is pretty certain to protect your portable toilet anywhere in the coldest climates in the US.


Some users appreciate the simplicity that simply pouring in methanol provides over the mixing necessary with the previous crystalline methods. With Methanol, you can add methanol into the toilet’s water in order to provide protection as far as -9°F.

It is important not to exceed safe amounts because methanol is a highly flammable substance that can cause the entire mixture to become flammable. Even within this amount, long-term exposure is inadvisable because fume exposure can be harmful to health.

Methanol and Rock Salt

If protection down to -9°F is not enough, then you can add rock salt in addition to methanol to acquire greater protection. By adding rock salt and methanol into the clean fresh water, you can acquire protection down to a low of -40°F.

Switch Out your Porta Potty 

When the portable toilet is placed in an area too cold for normal anti-freezing methods (unlikely in Seattle area) or they are just too inconvenient, there is another solution. Remove the frozen toilet and switch it out with a clean, fresh, thawed out toilet.

Place Your Portable Toilet Inside

Nothing says a portable toilet has to be outside. Especially in the winter you can always relocate your Green Latrine inside and out of the freezing temps.

Will Freezing Damage my Portable Toilets?

No. Freezing does not cause damage to a portable toilet. Plastic portable toilet waste tanks with an open toilet seat can freeze without damaging the toilet or damaging the waste tank itself. We all know liquid expands when frozen and in a glass or sealed plastic water bottle those examples of frozen liquid expanding can cause damage. But not the case in plastic porta potties. Nothing bad will happen to the plastic porta potty if it freezes.

Using a frozen Porta Potty – Can I go to the bathroom in a frozen portable toilet?

Yes. You CAN use the restroom if the portable toilet is frozen. A frozen waste tank will prevent us from pumping out the waste. We can not pump frozen liquid waste. But you can absolutely use your Green Latrine portable toilet if the waste tank freezes.

Can I Place My Porta Potty Inside?

Absolutely you can put your porta potty inside. Particularly common in large buildings like a barn, warehouse, large garage, carport, or parking structure.  Our Green Latrine porta potties are tall and wide and don’t often fit in through a standard door. You’ll need a large door, like a garage door. And once through the door you’ll need plenty of ceiling height. Inside portable toilet placements can be an issue for smell but typically in winter months smell really isn’t a problem. It’s the warmer summer months in Seattle when smell could become an issue if you place your Green Latrine porta potties inside.

Contact Us

For the best in Seattle, Tacoma, Everett, Bellevue portable toilet rentals, it’s impossible to beat Green Latrine. Since 2015 we have been helping to serve customers to get the portable toilet rentals they need, we will help you find the best option for your event or construction site or any other type of site that requires a portable bathroom.

Call us at (206) 397-0336 or email us at

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