Types Of Septic Tank Additives – Efficacy, Pros And Cons

There are many septic tank additives out there from different manufacturers with promises to enable you to get the best from your septic system.

While this might sound like a good idea, you must consider many issues before adding additives to your septic tank.

In this article, we will discuss how a septic system works, the different types of septic tank additives, how they work, and their effects.


Septic tank additives are biological agents or chemical products purchased for one’s septic tank to carry out various functions such as:

  • Breaking up scum in the system.
  • Accelerating biosolid digestion.
  • Increasing the settleability of solids in the septic tank.
  • Unclogging a clogged soil absorption system.


One needs to understand how a septic system works before considering getting additives or not.

A conventional septic system that comprises a tank, drain-field, and soil; works in such a way that it doesn’t require any human intervention. The septic tank is designed to help keep solids, oil,  grease, etc., from entering and clogging your drain field.

The septic tank receives all household wastewater and waste solids.

Bacteria from the waste then break down the solids separating the waste into different layers. The solid such as sand and dirt create a layer at the bottom known as sludge, while grease, fats, etc., rise to the top to create a scum layer.

In the middle is a layer of clear wastewater called effluent, which passes through a drain field into the soil. This is where it undergoes further filtration before safely being integrated into the groundwater.

When properly maintained by regular inspection, pumping, etc., a septic system could function for as long as 20 years or more.


Man, in his usual manner, has tried to mitigate the natural treatment process in a septic system resulting in the manufacture and marketing of specific septic additives to enhance the smooth running of septic systems and solve possible problems.

This brings us to the different types of septic system additives.

Many septic tank additives manufacturers claim their products carry out many functions such as digesting solids in a septic tank, breaking up scum in the system, accelerating biosolid digestion, etc. They also claim their products refresh one’s strategy, so you don’t need to pump your septic tank more often.

There are two main categories of septic system additives. These include;

BIOLOGICAL ADDITIVES: This group of additives contains yeast, enzymes, and bacteria that help to enhance and boost newly installed systems; and augment overworked ones.

In reality, one does not need any bacteria to be added to the septic system as the bacteria which comes from the simple act of using the system is sufficient enough to keep the system working fine.

CHEMICAL ADDITIVES: These could be either inorganic compounds or organic solvents.

The inorganic compounds contain strong acids or alkaline and are promoted for their ability to open clogged drains. They include sulfuric acid, formaldehyde, hydrogen peroxide, etc.

The organic solvents include chlorinated hydrocarbons that are commonly used as degreasers and can break down oil and grease. However, they can disrupt groundwater and wastewater treatment processes.

Chemical additives are used to break down sludge and oil; and control odor in a septic system.

When added, these additives are capable of killing the bacteria and other beneficial microbes that help keep the septic system working fine.

They can also destroy the waste separation process that takes place inside the septic tank, leading to contamination of the groundwater and surrounding soil. The chemical additives can also damage the system’s pipe and other components.

For example, research has shown that hydrogen peroxide though not much harmful to bacteria, is capable of degrading soil structure in a drain field, thereby reducing its ability to purify wastewater effluent.


It has been approximated that over 1200 additives products are in the market today, many of which contain enzymes you can buy from chemical companies, discount stores, etc.

Although the beneficial effects of biological additives on the septic system are still being debated, you might have discovered some benefits.

Firstly, under septic tank bacteria “die-off” conditions,  slight reductions in the amount of effluent solid have been achieved using additives.

Die-off conditions in this context occur when toxic substances like bleach and disinfectant cleaners in large quantities destroy bacteria in the septic tank. Other factors that can also cause die-off include the use of some anti-bacterial agents and medications taken by the homeowner.

Secondly, some enzymatic products can reduce the amount of grease and oil in the septic tank.

Studies have also shown that chemical additives like alum, baking soda, and hydrogen peroxide, when used in a septic system, could agitate soil containing clay and silt, destroying the soil structure and decreasing the soil permeability.


It may not be a good idea for a homeowner to use additives in their septic tank that is designed, operated, and maintained properly.  The reason is that naturally-occurring bacteria needed to make your system work properly are present within human fecal matter.

You don’t need to add a more, feed, or support them. Also, contrary to popular belief, yeast and possums are not required in a septic tank.

It is also worth noting that adding chemical additives to a septic system may lead to the death of the bacterial population in the septic tank, destroy the structure of your tank and pipes, and might also lead to groundwater contamination.

Septic additives are unnecessary as a healthy septic system has all it takes to treat and get rid of water. All your tank needs to stay in shape is regular inspection and cleaning to remove the solid sludge layer.


So, what can you do to keep your septic system running fine without additives?

Below are some maintenance tips you ought to follow to maximize the life of your septic system and get the best of it.

  • Using less water as excessive use could be a significant cause of system failure. It prevents the drain field from absorbing water efficiently, leading to an overflow problem. Also, repair any leak immediately after it is noticed.
  • Properly dispose of paints, pesticides, and oil at their garbage place and prevent toxic materials from going down the drain.
  • Leftovers from food, medications, tissues and other solid items should go to the trash bags and not down your septic system.
  • Space your laundry throughout the week to avoid overloading, as doing all of it one day might strain your drain field.
  • Having your tank checked routinely for any faults is another excellent way of having your system clean and in good condition.
  • Also, have your septic tank pumped when needed, depending on your household size and how often you use it. This is necessary to remove the accumulation of solids from your septic tank.

Septic tank pumping can be likened to changing the oils in your car. Doing it regularly will prolong the life of your engine, and not doing it at all will lead to the machine’s demise.


Although it is not necessary to use additives when a septic system can carry out its primary function.

However, there are instances where one can still use additives, especially biological ones.

Some homeowners do not stay home that often, so the septic system lies unused while they are gone. This means that the tank will not get the necessary bacteria it is supposed to get from everyday waste.

In such cases, the bacteria in the tank might not be enough to carry out a proper breakdown. Infrequent use can also cause solids to accumulate more quickly than average, and in such a scenario, you may consider using septic tank additives.

You can still solve this problem without additives by saving heavy water-use activities such as laundry or dishwashing until the toilet has been used a few times to generate more bacteria.

Another instance one can use a biological additive is when homeowners take antibiotics or other prescribed medications that may reduce the number of bacteria being released into the septic system.

However, it should be noted that there is still much research in this area.

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