How To Insulate A Septic Tank [7 Options To Consider]

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Normally, there is no interference with the decomposition of waste in your septic tank when the weather is warm. However, the freezing temperatures during winter could interfere with this process. We have consulted with the experts to tell us more about how to solve this problem.

To prevent your tank from freezing during the cold season, which could prevent waste in the septic tank from breaking down, use one or more of the insulation methods below:

  • Cover with a blanket.
  • Cover with a layer of mulch.
  • Allow growth of grass/vegetation.
  • Use Insulation sheets.
  • Bring riser lids to grade.
  • Keep away human and vehicle traffic.
  • Use a tank heater or heat tape.

Continue reading for an in-depth discussion on the insulation methods and the potential problems posed by a frozen septic tank. Also, you'll get to understand what you should and shouldn’t do when your tank freezes and how to maintain it in good condition to last longer.

Concrete septic holding tanks being buried for a new home construction, How To Insulate A Septic Tank [7 Options To Consider]

The Basics of Insulating Your Septic Tank

Concrete septic holding tanks in the ground

The bacteria in the septic tank feed on the waste matter, thereby decomposing it. This process is normally impeded during the cold season. So, what should you do?

Protect your tank from freezing so that the liquid and water in the septic tank do not also freeze. Otherwise, the sewage may flow back into your home, creating a mucky mess and a myriad of health concerns.

You can avert these problems by insulating your tank to allow the bacteria to continue breaking down the waste. This means insulating the tank, drain pipes, drain field, and sewer lines.

The first step is to make sure that all the openings including inspection pipes, risers, and manholes have tight lids covering them to prevent cold air from entering the sewer system.

Afterward, you may incorporate at least one of the following insulation methods:

Cover With A Blanket

Check out this frost blanket on Amazon.

Don’t wait for winter to set in before insulating the septic tank. As autumn comes to an end, cover the entire septic system with a frost blanket, including the tank, sewer lines, and drain field.

For your tank to keep warm during winter, the blanket ought to have an R-value of 1.5. An additional quality of the blanket is that it is waterproof and snow-proof. 

Did you know fresh snow is a splendid insulator? Despite containing 7 percent water, it is similar to fiberglass insulation with an R-value of 18. Therefore it is an added advantage when snow falls on the blanket.

Cover With A Layer Of Mulch

Another method of insulating your tank is to lay down a layer of mulch 8 to 12 inches thick over the tank and sewer lines. It consists of loose materials like straw, hay, or leaves. 

This method is excellent for recently installed septic systems since there is no vegetation to cover them. Anyhow, if your septic system is already frozen, do not add any mulch because it will delay the thawing process by the time spring arrives. 

Allow Growth Of Grass/Vegetation

If you happen to install your tank much earlier before winter starts, then you can allow the vegetation or grass to grow over the septic system. This will insulate your tank by holding the snow when it falls.

Use Insulation Sheets

Have a look at this foam board insulation on Amazon.

You can place insulation boards with an R-value of 10 on the sides and top of the tank before you back-fill. As you do so, remember that the higher the R-value, the better the insulation your board will provide.

Bring Riser Lids To Grade

Have a look at this spray foam on Amazon.

If your septic tank does not come with a pre-insulated riser cover, then you can insulate it by spraying foam on top of it. You could also cover all around the riser with a flexible insulation board.

Butmake sure that you are not using spray foam or flexible insulation as a quick fix to poor installation of the tank’s opening. Damages to the tank should be repaired promptly before insulation.

Keep Away Human And Vehicle Traffic

The pockets of air in between loosely compacted soil or snow helps in insulting the septic system. That is why vehicles and traffic of human activities that would cause the ground to be compact should be kept at bay.

Use Tank Heater Or Heat Tape

It may be inevitable that your septic tank will freeze if you live in areas with very cold climates. This means you will need to use a more applicable method such as the tank heater or heat tape. We shall briefly look at how each works:

Tank Heater

If the insulation methods described above are not effective because the weather is too cold, or you want an instant solution; then the tank-heater heater is your best option.

The automatic heater is turned on when it receives a signal indicating that the temperature has dropped below the minimum required level. You have to turn on the manual heaters when the temperatures begin to drop.

To use this heater effectively, first, identify the vulnerable spots where frost has the highest chance to form. It could be the tank, drain field, or anywhere within the septic system.

Heat Tape

Heat tape is also used if the temperatures are too cold. The tape is wrapped on the pipe and works by transferring heat to the pipe after connecting it to an electrical outlet.

Click here to see this heat pipe on Amazon.

What Should You Not Do When Your Tank Freezes?

Septic tank near the foundation. Autonomous conolization.

Sometimes your tank may end up freezing, causing you to panic. If you find yourself in this situation, call a professional. 

As a caution measure and maintain your septic system in good condition, do not attempt any of the following:

Do Not Add Salt 

Do not try to antifreeze by adding salt to the system, as this could jeopardize the natural working of the bacteria in the tank. Also, salts could be toxic to your drainage field by killing the vegetation.

Do Not Run Water 

Running water continuously will not thaw the septic tank. You will waste a lot of water, not solving your problem.

Do Not Pour Hot Water

You might think this is a good solution, but pouring hot water into the pipes may cause them to burst if there is a blockage. 

How Can You Prolong The Life Of Your Septic Tank?

Septic tank installation for wastewater treatment system

It can be very expensive to replace not only a septic tank but the entire sewer system in your home.

Thus, you need to know what you can do and should not do to give your tank a much higher chance of lasting longer. This is shown in tabular form below:

What You Should Do What You Should Never Do
Protect the area where the septic tank is, to prevent the soil from compacting. Never add caustic chemicals into the tank as this can interfere with the natural decomposition of waste.
Keep a track record of all the maintenance and repairs. Do not plant shrubs or trees near the sewer system as the roots may grow long and affect it.
Ensure the tank cover is accessible. Never construct over the drain field.
Keep the sketch of your sewer system safely as it can come in handy when locating the components. Nothing else but waste should find its way into the tank.
Have a keen eye on the earth settling as it could direct water into the drain field. Do not water too much the grass and vegetation around the system.
Ensure the vegetation or grass is growing around the sewer system for insulation purposes. Never drive or park on the drain field.

In Closing

A worker installs a sewer manhole on a septic tank made of concrete rings.

The septic tank is very useful in our homes as that is where all the waste finds its way. If it is not in good working condition a lot of things in the house can go wrong.

For the tank to continue working properly during winter, one needs to prevent it from freezing. There are various methods to make sure it does not freeze.

If your tank happens to freeze, do not attempt to thaw it, but call a professional. You will prevent damage from occurring, and your tank will last longer.

You may want to read our previous posts and find out if you can double-insulate pipes and the insulation levels of spray foam:

Can You Use Foam Pipe Insulation Over Heat Tape?

R-Value Of Spray Foam Insulation

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