About 8 years ago I had a frozen
septic tank situation occur in one of my homes. The septic tank froze due to
a number of factors. First, the winters are cold and hard in the particular
area of the country where the home is located. Second, the home is rarely
used during the winter months. Third, the tank is only covered with about 4
inches of topsoil. Fourth, though it was extremely cold there was no
insulating snow on the ground. Lastly, the drain pipe that exits the house
and feeds into the septic tank is only buried with about a foot of soil.
The depth of the soil over the
septic tank and the drain pipe may not be much of an issue in warmer
climates, but in northern climates where the frost can be up to 4 feet deep,
this can be a real problem for septic tanks. In retrospect, I shouldn’t have
been surprised to have found a frozen septic tank when visiting the home.
Symptoms of a Frozen Septic
It is fairly easy to determine if
you have a frozen septic tank. In my case, we had just arrived at the home
and started flushing toilets and even doing a load of laundry. Due to the
fact that the septic system is a pump up system, the frozen septic tank
wound up backing up water into the house, and in particular the lower level
bathtub. As soon as I saw sewage water filling up in the tub, I immediately
shut of the faucets, clothes washer and the well pump.
Using a pickaxe I was able to
remove the 4 inches of topsoil from around the septic tank cover and lift
the lid of the tank. As I had expected, the tank had a couple of inches of
ice encrusted on its surface. I was able to chip through it with a steel
pipe, and find the liquid effluent sitting just below it. I also checked to
see if the septic tank baffles were encrusted with ice. Fortunately they
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I then went into the basement of
the home, and removed the large PVC drain plug/nut to the drain pipe that
exited the house. I also held a 30 gallon trash bucket underneath the PVC
drain plug/nut as I knew the sewage water built up into the drain system
would come pouring out, which it did. Needless to say, I got a little wet
and dirty at the same time.
Unfreezing a Frozen Septic
After inspecting the drain pipe,
I determined that it was frozen as well.
Photo by Mark Donovan
After emptying the 30 gallon
trash can of sewage water, I then placed it underneath the drain pipe and
connected one end of a hose to the water heater and the other end deep into
the drain pipe. I then turned on the well pump and the valve to the hot
water heater. After about 10 minutes of running the hot water into the drain
pipe, and catching a lot of it in the trash can, I melted a hole through the
ice in the drain pipe so that water began to flow again into the septic
I continued to run the hot water
into the tank for about another 15 minutes to unthaw as much of the frozen
septic tank pipe as possible. I also did this, to make sure the pump located
in the septic tank was working correctly. I could actually hear in the drain
pipe the septic tank pump turn on and pump up effluent to the leachfield.
Once I was sure the frozen septic
tank was unthawed, at least to let a level where it worked again, I screwed
in the large PVC drain plug and covered the septic tank with the frozen
soil. In addition, I bought several bales of hay and spread about 12 inches
of hay over the septic tank and the drain pipe area to provide some
Later on that spring I had the
septic tank pumped and inspected. Fortunately there were not cracks, and the
baffles and pump were not damaged.
Since my frozen septic tank
experience, I installed some insulation around the drain pipe and added more
topsoil over the tank and drain pipe. In addition, late each fall I have the
septic tank cleaned, and cover the top of it and the drain pipe area with
some hay. Many years have passed since that frozen septic tank experience
and I have yet to have the situation reoccur.
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