Are septic tank additives good or bad?

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

Septic tank additives are sold to homeowners across Canada, but they lack regulation, standardized testing, and formal certification. That can make it hard to know if septic tank additives really work, and if you need them at all.

To find answers, we will divide additives into three categories: inorganic compounds, organic solvents, and biological additives.

Inorganic compounds

Septic tank additives with inorganic compounds include acids and alkalis. They are meant to unclog septic system pipes. While these harsh 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 septic systems)

Organic solvents

Septic tank additives with organic solvents are meant to break down fats, oils, and greases. Again, even though these products may work, we suggest you avoid them because they:

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

Biological additives

Biological septic tank additives include yeasts, natural bacteria, and enzymes. They are meant to improve the bacterial flora in septic tanks and drain fields, control biomass, and reactivate 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.

Healthy septic tanks already have enough bacteria to support the biological processes that treat human waste and wastewater.

By adding more bacteria in the tank, you create conditions in which bacterial populations compete against each other. This competition can do more harm than good.

Unhealthy septic systems are a different story. Often, the bacterial flora in these systems has been destabilized by large amounts 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 find out 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 (also known as bio enzymes) are meant to stimulate bacterial populations in septic tanks. They do this by changing the structure of organic matter so that bacteria can feed on it more easily.

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

  1. They are specific
    For example, take two common enzymes: cellulase and protease. Cellulase breaks down only toilet paper and other fibrous materials. Protease breaks down only protein-based pollutants. These enzymes have no effect on other organic contaminants.

  2. They are not alive and cannot reproduce
    Unlike bacteria, 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, damage their performance, and shorten their lifespan.

The verdict on septic tank additives

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

It may be hard to decide if septic tank additives are good or bad. This article, the scientific community, and the environmental regulations in your area can help you make an informed decision.

What science says about septic tank additives

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

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

Septic regulations near you

Many septic additives claim to eliminate the need for septic tank pumping. Even if these claims are true, they are often irrelevant.

In addition to organic waste, raw sewage contains minerals, synthetic fibres, plastics, and other solid waste. No amount of septic tank additives will break down these materials. They build up as sludge at the bottom of your tank and stay there until a septic pumper removes them.

The build-up of sludge is inevitable, and local authorities know it. That is why most jurisdictions require homeowners to have their septic tank pumped on a regular basis. No matter how much you spend on septic tank additives, you still need to follow these maintenance 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 and regular septic tank pump-outs.

For advice about septic services in your area, contact our team of experts. We are always here to help.

Talk with an expert

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