The exposed access port of a septic tank in a yard covered in snow.

Seasonal Care for Septic Systems: The Most Important Winter Tasks

ByLaura Schultz

Winter, at least in areas where the season gets cold, is arguably the most critical season for homeowners to properly and diligently take care of their septic systems. 

In winter months, septic tanks are vulnerable to damages caused by low temperatures and excessive snow. The biggest resulting concerns are typically snow buildup and lack of protection from cold temperatures. If a septic tank is located in an area where vehicles can drive over it, compacted snow can push frost deeper into the system. Fluid that lingers in poorly installed or deteriorating pipes, plumbing leaks, and long periods without using a septic system can all cause it to freeze. 

A septic system may suffer damages if it is not provided adequate insulation, such as a riser cover or blanket. This will help to trap heat inside the system and prevent it from freezing inside. Other ways to help prevent septic systems from freezing are regularly pumping (about every 3-5 years) before winter, not disposing of inappropriate waste down toilets or drains, using insulated pipes, and removing trees or plants with strong root systems from the top of a system to prevent root interference.

Read on for further advice for dealing with septic systems during the winter to pass on to homeowners, as well as guidance for any maintenance work that must be performed in winter weather.

Steps to Prepare for Winter and “Winterize” the System

Without proper preparation for the season, the freezing temperatures of winter are more likely to cause a septic system’s pipes to burst, tanks to freeze, and overall systems to fail. And, should any of these things happen, the cold weather and frozen ground will make repairs more difficult. Here’s what to advise homeowners to do before the weather gets too cold.

  1. Schedule pumping, if needed, before winter — it’s substantially harder to do in the cold (more on that below).
  2. If pumping isn’t scheduled, try to minimize waste entering the system so that it is not overfilled for the winter. 
  3. Check for leaks, and not just in your septic system. Any plumbing fixture attached to the system should be checked as well — Small trickles of water in the pipes are more likely to freeze and create a buildup of ice. 
  4. Pipe and tank protection: Make sure exposed or shallow pipes are covered and well insulated with soil or other appropriate material. If you’ll be away for a long period of time, drain the system’s pipes to prevent pipe freezing. For tanks, the aforementioned riser covers or blankets can help prevent lids freezing.
  5. Keep the grass long on top of the system and drainfield for additional insulation. 
  6. Use the system regularly during the winter to keep it from freezing. Flowing water is critical in freeze prevention.

What Happens When a System Freezes?

Septic systems can freeze in many locations. The most common includes the pipes from the house to the tank, the septic and/or pump tank themselves, the pipes from the system to the drainfield, and the drainfield/soil treatment area themselves. Septic professionals should be able to determine both where and why a system froze, and how to prevent that freezing from reoccurring. 

There are many factors that can contribute to the freezing of a septic system. Those include lack of snow cover (as ironic as that may sound), compacted snow and/or soil, lack of plant cover, irregular use of a system, leaks, and more. Signs of a frozen system can be similar to those of a clogged system, such as slow-draining sinks/tubs/toilets, blocked drains, and sewage backup. Another likely sign is the sound of running water in the pump tank if one is present.

Should a homeowner notice these signs in winter, and particularly the running water in the tank, they should be sure to shut off the pump and call a septic professional to help determine the source of the problem and how to fix it. It is important to note that if the issue is not corrected, the system will inevitably freeze again. 

There are several things to make sure a homeowner does not do to address a frozen system. These include adding antifreeze, salt, or additives to a system; pumping sewage onto the ground surface, starting a fire over the system, and running water constantly in the house. Conversely, there are many options available to help prevent future freezing. Many solutions have already been referenced, from increasing insulation to fixing leaks to limiting the traffic (both of humans and cars) above a system. More can be found at the University of Minnesota Onsite Sewage Treatment Program’s Seasonal care guide.

Pumping During the Winter

Unless your local “winter” does not involve the ground freezing, the season is simply not a good time to perform septic pumping. One self-evident reason is that it’s harder to access and open the tank, especially if the access port is buried and not at-grade, due to frozen ground. Additionally, freezing in the drainfield becomes more likely after winter pumping because it will take days or weeks for the system to fill back up with water. The bacteria breaking down the wastewater will also take longer to get back to full operation in the cold weather than they do in warm weather.

However, emergencies can occur in the winter that necessitate pumping. Sewage backups into the house or yard and pump failure are such emergencies that warrant the labor of winter pumping. If it’s determined that pumping is necessary, it should not be delayed in order to limit the risk of sewage backup, which would likely be a worse problem than the weather. 

Staying Safe When Working In Winter Weather

If you find yourself pumping a septic tank or performing other urgent maintenance during the winter months, it is critical to stay safe and warm. Always bring extra clothing, and have a warm place to retreat to in order to escape the cold. Remove excess snow from work areas and store equipment either under tarps or in heated areas.

Here are the things to watch out for when working outside in extreme cold:

  • Wind Speed: High wind speeds can create a wind chill effect, which makes it feel a lot colder than the reported temperature.
  • Humidity: Humidity will cause heat to be conducted from the body much faster than when working in dry air. 
  • Hypothermia: Without proper protection, hypothermia is a concern. While most common at very cold temperatures, it becomes possible in the range of 30°–50° F with prolonged exposure. Being wet and/or sweaty will make it more likely at any temperature under 50° F. 
  • Frostbite: Exposed skin can freeze in any temperature below freezing (32° F). The colder it is, and the lower the wind chill, the faster the skin will freeze. When the temperature is around 0° F skin will freeze in about 30 minutes.
  • Ice & Snow: Ice can freeze your equipment and the weight of snow can collapse structures you may be working in or under.

Go to OSHA’s Winter Weather hub or Cold Stress Guide to learn more about staying safe on the job in winter.

Sources and Further Information:

  1. Seasonal care at the University of Minnesota Water Resources Center, Onsite Sewage Treatment Program
  2. Expert Advice for Maintaining Your Septic Tank This Winter, Wind River Environmental
  3. Winterizing Septic Systems: A Quick Checklist, Onsite Installer
  4. Five Winter Septic System Maintenance Tips, Infiltrator Water Technologies
  5. Guidance for Septic Systems Before, During, and After Winter Weather; National Environmental Health Association