By Jerome Fife
Let’s discuss a topic that might be well-known or perhaps not: the use of additives in septic tanks. This topic often raises two main questions: Is it advisable to add substances to my septic tank every month? And when my septic system seems to be failing, should I start using additives? Here’s my perspective on these inquiries.
Predicting the exact moment a disposal field will fail is impossible. We can only rely on historical data regarding the average lifespan of disposal fields, which typically ranges from 20 to 25 years.
When a disposal field approaches the end of its life due to age or shows early signs of failure, it’s generally not advisable for homeowners to introduce bacteria, enzymes, or chemical additives into the septic tank monthly in hopes of prolonging its life. In fact, adding these substances regularly throughout the septic system’s operational life is even less recommended. Although it is difficult to prevent this practice, health departments do not explicitly ban it; they do, however, discourage it for good reason.
The primary function of a septic tank is to isolate and eliminate bio-solids from wastewater by separating them into solids that sink and those that float, aided by intestinal bacteria within the tank — this process is known as “primary treatment.” The bacteria present in your waste do not digest organic material in the septic tank (just as they don’t in your intestines), but they help break down solid materials into smaller particles that can settle at the bottom, forming sludge, while lighter solids rise to create a layer called scum. This process effectively removes approximately 70 to 90 percent of the solids introduced into the water to exit your home through gravity. To optimize this process, effluent must remain in the septic tank for a sufficient retention time. This is why regular pumping is necessary: to eliminate accumulated solids and maintain the liquid capacity and retention time within the tank’s design limits. Introducing monthly additives disrupts this sequestration process.
The additives — whether bacteria, enzymes, or chemicals — can decompose some of the trapped solids and enable them to exit the tank prematurely, traveling suspended within the effluent to the disposal field. There, they can form a solid sludge layer that may shorten the disposal field’s functional lifespan. Homeowners may feel reassured by less frequent pumping, but this belief is misleading. They are not actually removing solids from their system; instead, they are merely relocating them to another part of it — the disposal field. This practice can potentially lead to a decrease in the disposal field’s effectiveness, which could be far more costly than any savings on pumping.
If you are prepared to pay for an overpriced replacement of your disposal field, then my concerns about additives may not apply to you. However, if you want to protect the longevity of your disposal field, it’s wise to avoid adding these bacteria, enzyme, and chemical products to your septic tank. Allow the tank to function as intended for sequestration and ensure regular pumping. The cost of pumping is minimal compared to the expense of an early disposal field replacement.