Sealed Septic Tank: Importance & FAQs
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Does a Septic Tank Need to Be Sealed?

Large IBC tanks on the side of a green building. The tanks are covered in metal cages and fences.

Septic tanks are a necessary part of your property's drainage system. They treat the wastewater coming from your home or business and protect the environment from contamination. 

In this article, we will discuss the various methods available for sealing a septic tank and explain why it’s important that it's done properly.

What is a Septic Tank?

A yellow plastic septic tank with a black septic pump.


A septic tank is a watertight container constructed out of either concrete, fiberglass or polyethylene and buried underground. It holds solid waste particles and allows liquid waste to flow through to a drainage or leach field. 

Not only do these systems promote the biological decomposition of wastewater, but they also minimize the release of toxins into the soil. This settling process is instrumental in reducing the level of pollutants that may contaminate our aquifers.

Why Should It Be Sealed?

Sealing a septic tank protects against water leakage and sewage backup, which can cause serious property damage. To ensure they are functioning properly, septic tanks must be entirely watertight.

A tight seal should exist between both the riser and the top of the tank, as well as between the cover and the riser. A tight seal will prevent any liquids from entering or escaping your system. Water entering the system can be as dangerous as water escaping. If your septic system fills with water, the pipes can become blocked and the solid waste has no room to enter — a recipe for a sewage backup.

There are several sealing methods available, and all are designed to provide a superior level of protection. Properly sealed tanks should last up to 20 years with minimal maintenance required.

Different Methods of Sealing a Septic Tank

When it comes to properly sealing a septic tank, there are three typical methods available for homeowners to choose from. These include butyl sealants, asphalt-based coatings, rubberized liners and elastomeric coatings.

Butyl Sealants 

Butyl sealants are rubber-like materials commonly used to seal septic tanks. They create an airtight barrier that prevents any liquid or gas from passing through. The butyl sealant is applied around the tank's lid to form a water-tight seal. These sealants are known for their flexibility, durability and resistance to chemicals, which makes them an ideal choice for sealing septic tanks. Additionally, butyl sealants are highly resistant to extreme temperatures, so they are suitable for areas with varying climates.

Asphalt-based Coatings

Asphalt-based coatings are the go-to choice for septic tanks due to their affordability and ease of application. Not only do they create an airtight seal that lasts up to two decades with minimal upkeep, but they also make DIY projects a breeze! Although rubberized liners are another viable option, asphalt is by far the most popular solution on the market.

Rubberized Liners

Rubberized liners are designed to snugly fit over all the sealed areas of your tank to form a watertight seal. Not only is this material incredibly durable, but it also offers superior protection against water leakage, sewage backups and UV rays, ideal for outdoor tanks in warmer climates! An elastomeric coating is an additional third method that provides optimal sealing protection for septic tanks.


Elastomers are materials that can stretch and return to their original shape after being subjected to pressure or strain, which makes them perfect for creating durable seals around sealed areas of septic tanks without affecting the tank's performance or draining capabilities.

Potential Problems if the Septic Tank is Not Properly Sealed

If your tank is not sealed properly, it can lead to serious problems. For instance:

Environmental Hazards

A robin standing in the shallow end of a muddy pond. The reflection of the robin can be seen in the pond water and there are various green plants behind the bird.


Unsealed septic tanks can be a major environmental hazard. By allowing wastewater to move through the soil and into underground aquifers, an unsealed tank can contaminate drinking water for years to come. Even if the tank is not leaking, it still poses a risk as the water table moves and passes by the area of the tank.

The release of untreated sewage in our groundwater contributes to harmful algal blooms and eutrophication which can make lakes, rivers and streams uninhabitable for aquatic life. 

Property Damage

The outside of a brick building with the bottom portion of stone that has deteriorated. Next to the building there is snow covering the ground.


An unsealed septic tank can also damage residential properties. If allowed to leach into nearby homes, wastewater from an unsealed septic tank could cause property values to decrease as well as costly damage repairs on foundations and plumbing systems. 

Homeowners must be aware of any possible leaks or damage that their septic system may be causing so that they can take action before things get worse. Taking precautions like sealing tanks and properly maintaining your septic system will help protect both your property and the local ecosystem.

Tank Depot is Your Best Resource for High-Quality Septic Tanks

Are you looking for a reliable septic tank provider? Look no further than Tank Depot. We have an extensive selection of high-quality tanks to meet any application, plus we guarantee the lowest price! With our quality assurance and helpful customer service team, you can trust that you're getting the best value for your money. 

Contact us online or call today to find out what our experts at Tank Depot can do for you!

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