Reduce Risk of a Frozen Septic System

Reduce Risk of a Frozen Septic System

Although there are many predictors, ranging from the width of bands on the wooly bear caterpillars to the Farmer’s Almanac, we never know what kind of winter we’re in for. When thinking about septic systems, a heavy snowfall that stays all winter is a good thing, because it insulates the system from the cold. Bitterly cold temperatures for a week or more with little snow cover can lead to a frozen system. There are a number of things you can do to reduce the chances of a frozen septic system this winter.

  1. If you don’t remember having your septic tank pumped, have it pumped and the system checked by a certified pumper before the ground freezes. Professionals recommend having the system pumped every 3 to 5 years, although the ideal interval varies depending on water usage and the size of the system. However, 15 years between pumping is too long!

  2. Let the grass over the pipes, tank, and soil treatment system get a little longer in the late summer/fall. This will provide extra insulation and help hold any snow that may fall. Place an 8 to 12-inch layer of mulch over the entire system to provide extra insulation. This mulch could be straw, leaves, hay, or any other loose material that will stay in place and will not compact. This is especially important if you have had a new system installed late in the year and no vegetative cover has been established.

  3. Use water, the warmer the better if your system is starting to freeze. Normally we advocate water conservation, but if freezing is a concern, increase your water use from low to normal. Do at least one warm/hot water activity per day, such as a load of laundry, using your dishwasher, or taking a hot bath. Never leave water running all the time, as this will overload the system with too much water.

  4. If you know you are going to be gone for an extended period, plan accordingly. Have a house sitter flush the toilet, run some hot water, and maybe even do some laundry; in other words, use sufficient quantities of water in the home regularly. Otherwise, have your tank pumped before leaving. One word of caution about empty tanks- if you live in an area with a high water table, only have the tank pumped if it was designed for high water table conditions; it may “float.” Also, some plastic tanks may not be able to withstand soil pressures if left empty. If a tank is left full for several winter months when no one is using water, the sewage will get very cold in shallow tanks and can even freeze in very cold temperatures. If you return home before temperatures start to rise, the effluent leaving the tank will be cold. By starting with an empty tank, you can start fresh with warm effluent. If you use a cabin on a limited basis during the winter months, this may be a good idea as well.

  5. If you have appliances that generate very low flows such as high efficiency furnaces, put a heat tape on the pipe, and while on vacation have someone come by and run warm water for a while. Alternately, you could install a small condensate pump that holds and discharges 2 gallons per cycle.

  6. Keep all types of vehicles and high traffic activities off the system to avoid pushing frost down toward system components. Keep an eye on your system. If any seeping or ponding occurs contact a certified onsite professional to help determine the cause and remedy.
    Adapted from Freezing Problems and Septic Systems, Ken Olsen and Sarah Heger, University of Minnesota Extension. 

Jan Hygnstrom
Jan Hygnstrom
Former Project Manager, Agronomy & Horticulture

Jan Hygnstrom shares timely information about plants you might see on your acreage and topics related to managing onsite waste water systems. Jan's background includes a horticulture degree and work in UNL's Departments of Biological Systems Engineering and Pesticide Education. In 2001, along with several colleagues, Jan helped lay the groundwork for the formation of NOWWA, Nebraska's professional organization for those in the waste water industry. NOWWA works to protect human health and the environment by ensuring the proper handling of onsite waste water systems.