How to prepare Septic Systems for the winter season?

Posted on 15 Jan 2019 by Fabian Belin

A short guide to preparing Septic Systems for the winter season

Many residences are seasonal in cold climate countries. Shutting down septic tanks and sewage treatment plants for the winter is of the highest importance for seasonal homeowners to extend the life of their septic system and septic tanks and to keep it in good operation. Precautions that will be taken during the fall season will help prevent septic systems to freeze and avoid surprises in the spring.

The beginning of the winter season is a good time for a general inspection of septic systems. A good recommendation is to ensure proper drainage of water supply lines of the septic system before the winter. Check any flexible hoses to ensure they are drained completely. By ensuring that all water is out of the lines you will avoid freezing the pipes.

Flush toilets several times and add septic antifreeze to the septic tank. Note that automotive antifreeze or salts should not be added to your plumbing. After disconnecting electrical supplies to the pump, softener, dishwasher, or water heater you may drain them with a hose. All lines will be reconnected in the spring.

Furnace
If you are equipped with a furnace that will remain on for the winter then ensure that no water drips into the septic system. The dripping water may be re-routed to a floor drain or bucket for instance. Water entering in very small volume can freeze in time. All water from the furnace may be drained in case of shutting off of the furnace.
Pump out of the septic tank
You may be considering pumping the septic tank if the house will be closed for the winter, or in case it will be used a few times only. In case you live in a place with the presence of high groundwater table, pump out the septic tank only if it was designed for high groundwater table conditions. A septic tank that is left full for the winter months without being used will get very cold and sewage can even freeze inside. Re-starting the spring season with an empty septic tank when the temperature of the ground starts to rise again will allow you to start new with warm effluent. This may be desirable for the soil treatment area. If you are equipped with an electric aerobic treatment unit, make sure that the blower is shut off in case of a long absence. Always follow detailed manufacturer requirements. If you are equipped with a non-electric sewage treatment plant this will be of course not necessary.
Infiltration field
Avoid cutting the grass over the soil treatment area after the end of September. The grass will help capture snow which will provide natural insulation over the septic system, which may help prevent freezing of the septic tank. An extra layer of straw or leaves may be spread just over the septic system to provide additional natural insulation. Remember that all precautions taken in the fall may help prevent a frozen septic system and avoid any surprises in the spring!
Ventilation
Septic systems need a plumbing vent to ventilate the septic tank and evacuate gases. This pipe must remain open under all weather and use conditions. For homes used intermittently during the winter months, it can happen that vent pipes get dry, allowing gases produced by the septic tank to seep back into the house.

Indeed, with cold weather moisture vapor from the house may start to freeze when it comes into contact with the cold metal of the vent pipe. Low temperatures may cause more and more water vapor to freeze on the inside of the vent pipe, eventually until it gets frozen shut. This problem can even occur in occupied residences.

Septic tank gases generated cannot exit through a vent pipe that is frozen shut; instead, they may escape into the house through plumbing traps.

An insulated vent pipe can be the answer to this problem. Modifying the height and location of the vent is another possibility and may help.

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