Certain times of the year bring specific mechanical problems with use and temperatures. Air conditioning never breaks down in the summer, right? We don’t use it then, and often the underlying problem goes unnoticed until mid-August when you really need cool air.
Similarly, problems that arise with your septic system during the winter may have begun months earlier. Successful Farming’s website reports freezing in the system can occur due to poor insulation. Walking over the septic system can compact the soil, thus reducing insulation and creating a place for water to puddle and freeze later This can be prevented by obviously not permitting human or animal traffic over the area, but also allowing vegetation to grow over the drain field and connecting pipes. Long grass insulates and aerates the soil. Other problems can be traced to furnaces that emit water when functioning.
Inspect the septic system on a nice, sunny day. Check the caps on the pipes. If they are missing or damaged, cold air can infiltrate. Five minutes now might prevent hours of trouble later!
Inside the house, don’t treat your toilet or sink like a garbage can. The only items that should go into your septic tank are human waste, toilet paper, and water. Learn more here: https://www.epa.gov/septic/how-care-your-septic-system. The site doesn’t list additives but yeast, vinegar (with or without adding baking soda) or a commercial one such a Rid-x are often used.
The Oregon State Extension online catalog also has publications about water and septic systems: