Septic tank additives are a constant feature of our industry. Some people swear by them while others are not convinced. Additives have evolved over time to meet the changing demands and perceptions of our industry. Very few jurisdictions attempt to regulate the use of additives, and the lack of an established standard testing method has contributed to the confusion and uncertainty around them. This memo is intended to provide a bit of clarity regarding the various types of products available. It is not intended to be either an endorsement or condemnation of any product.
Additives are meant to help either the septic tank or drain field and fall into three categories: inorganic compounds, organic solvents; and biological additives.
Inorganic compounds are marketed to open clogged drains and are typically strong acids or alkalis. These products should be avoided as they can kill the bacteria in the tank and stop the anaerobic digestion process allowing raw sewage to pass out into the drain field. These products can also corrode concrete tanks causing leaks.
Organic solvents are degreasers which can be effective in breaking down fats, oils and greases. However, these products can also kill the bacteria in the tank and may lead to contamination of the ground water.
Biological additives such as yeast, bacteria and enzymes are used to enhance the existing bacteria and microbes in the tank and drain field, reactivate an “unhealthy” tank, or address a severe biomat buildup issue in the system. Yeast does help the process in a tank by breaking down starches within it; however, starches make up only a small percentage of the waste in the tank. It takes more than yeast alone to break down all the five types of waste (Proteins, Fibers, Greases, Pectins, and Starches) found in a normal septic tank. Enzymes are specific. For example, Cellulase, an enzyme that liquefies fibers (toilet paper), will only liquefy fibers and a protein-liquefying enzyme called Protease must be present to attack the protein-base wastes.
Bacterial based additives provide a boost of bacteria to an existing tank to help support or stimulate bacterial growth and action in the septic tank. Normally, a healthy septic tank and drain field contain enough bacteria to support the biological processes required for treatment without additional stimulation. However, in some cases the biology of the tank may not be “healthy” due to the addition of toxic substances such as pharmaceuticals, excess cleaning products, anti-bacterial soaps or other things that hinder the bacteria necessary for anaerobic digestion. In these cases a bacterial additive may be able to provide a boost to bacterial populations to promote and support a robust biological population in the tank. However in cases where bacteria are healthy, adding a commercial product may cause the new bacteria to compete with existing bacteria that are adapted to living in your treatment tank. This competition could be unhealthy, leading to reduced efficiency in the tank.
Enzymes, unlike bacteria, are not living and cannot reproduce. Enzymes are intended to stimulate the growth and reproduction of the existing bacteria in the tank in order to affect better treatment in the tank. To date, there is little scientific evidence to support the use of enzymes. However, some enzymes which breakup the scum layer may allow the fats, oils and greases held in the scum layer become free to enter the drain field.
Many products claim to eliminate the need to pump out the treatment tank. These claims should be treated with skepticism. Some of the solids in the treatment tank are sand, grit, bits of plastic and other similar non-biodegradable materials which cannot be digested or broken down by enzymes or bacteria and therefore, they accumulate. So far, independent third-party studies indicate that the use of additives does not prevent the accumulation of sludge. Degreasers may break down stubborn solids, but where do the solids go? If they stay in suspension they may go out to the leaching bed, which could increase the rate of clogging in the bed. A properly functioning and maintained effluent filter may help mitigate this risk. If you choose to use this type of product, be aware that there may be unforeseen consequences to less frequent tank pumping.
The science supporting the use of additives remains inconclusive. This is partially because the benefits are difficult to predict and often a trial and error process is required. In some instances supporting or enhancing bacterial populations may be helpful, even necessary to the proper treatment of effluent. If you think using an additive is right for your system, go to a trusted supplier for advice. They will help you choose the best additive for your system. Choose one that has the Eco-Logo symbol, which indicates that the product isn’t harmful to the environment. An engaged, responsive property owner who combines any potential additive use with proper septic tank maintenance, i.e. following sewer use guidelines, pumping and effluent filter cleaning, can only be good for our industry.