Are septic tank additives good or bad?

Man in overalls opening green septic tank lid with protective gloves.

Septic tank additives are marketed to homeowners around the world, but they often lack regulation, standardized testing, and formal certification. That can make it hard to know how well these products work, or if you need them at all.

What are septic tank additives?

Man shopping in supermarket reading product information.

Most septic tank additives are designed to improve the performance of septic tanks or leach fields (sometimes called drain fields). Additives can be divided into three categories: inorganic compounds, organic solvents, and biological additives.

Inorganic compounds

Inorganic compounds, such as strong acids and alkalis, are marketed as a way of unclogging septic system pipes. While these chemical additives may work as advertised, we suggest you avoid them because they:

  • corrode and cause leaks in concrete treatment tanks
  • stop the anaerobic digestion process in septic tanks
  • harm the bacteria that are essential to the wastewater treatment process
  • reduce the effectiveness of conventional septic systems
  • disrupt the performance of secondary treatment systems (including Ecoflo biofilters)

Organic solvents

Organic solvents are designed to break down fats, oils, and greases in septic systems. Again, even though these products may achieve their stated goal, we suggest you avoid them because they:

  • kill essential bacteria in septic tanks
  • negatively affect the health of conventional septic systems
  • impair the performance of secondary treatment systems
  • contaminate groundwater

Biological additives

Biological additives, such as yeasts, natural bacteria, and enzymes, are meant to:

  • improve the bacterial flora in septic tanks and leach fields
  • control biomass in septic tanks
  • reactivate “dead” or dormant septic systems

Do I need to add bacteria to my septic tank?

Person dropping a biological septic tank additive with bacteria and enzymes into their toilet.

Bacterial additives are designed to restore and support bacterial growth and activity in septic tanks.

Healthy septic tanks already contain enough bacteria to support the biological processes necessary for wastewater treatment. By adding more bacteria in the tank, you create conditions in which bacterial populations compete against each other. Ultimately, this competition can reduce, rather than increase, the effectiveness of your septic system.

Unhealthy septic systems are a different story. Often, the bacterial flora in these systems has been destabilized by large quantities of toxic substances, including:

  • certain soaps
  • disinfectants
  • cleaning products
  • medicines
  • pesticides

When this happens, bacterial additives may help you re-establish a healthy balance in your septic system. To determine if this step is right for you, contact your septic system manufacturer or ask our team of experts.

Do I need to add septic tank enzymes?

Additives with enzymes are meant to stimulate bacterial populations in septic tanks. They do this by simplifying the structure of the organic contaminants the bacteria feed upon.

There are two important things to know about septic tank enzymes:

  1. They are specific. For example, take two commonly marketed enzymes: cellulase and protease. Cellulase breaks down only fibrous materials, such as toilet paper, and protease breaks down only protein-based pollutants. For all other organic contaminants, these enzymes are ineffective.
  2. They are not alive and cannot reproduce. Unlike bacterial products, enzymes must be regularly purchased and added to your septic system to maintain their intended performance.

Some septic tank enzymes are sold to limit the build-up of a scum layer. They work by allowing fats, oils, and greases to flow downstream into secondary treatment systems and other septic system components.

The problem is that fats, oils, and greases are not meant to flow downstream. If they do, they can overload your septic system components, reducing their performance and shortening their lifespan.

The verdict on septic tank additives

Overhead view of a septic technician inspecting the wastewater and pipes in a septic tank.

In the final analysis, are septic tank additives good or bad? To decide, we recommend that you draw your conclusions from the scientific community and the environmental regulations in your area.

What science says about septic tank additives

There is little scientific evidence to suggest that you should add bacteria or enzymes to your septic system.

The United States Environmental Protection Agency (EPA) reported that biological additives do not appear to improve the performance of septic tanks. These same findings were unable to justify the cost of septic tank additives for residential use (EPA, United States, 2002).

Septic regulations near you

The makers of many septic tank additives claim that their products eliminate the need for septic tank pumping. Treat these claims with skepticism.

Raw wastewater contains minerals, synthetic fibres, plastics, and other debris. No amount of septic tank additives will break down these materials. They will accumulate in your tank until a septic pumper safely pumps them out.

This is just one of the reasons why jurisdictions require homeowners to have their septic tank pumped on a regular basis. Buying and using septic tank additives does not exempt you from these regulations.

Your next steps for a healthy septic system

The best thing you can do for your septic system is to have it properly maintained by a trained professional. That means close inspections, regular septic tank pump-outs, and an effluent filter that is cleaned as often as needed.

For expert advice about septic services in your area, or any other wastewater topic, contact our team today. We are always here to help.

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