Are Septic Tank Additives Necessary?

There are a lot of products you can purchase at the local hardware stores and online that claim septic tank additives, or septic system treatments, are advanced enzymes that break down household waste or natural active septic bacteria to reduce tank build-up and prevent septic tank backups. At Double Flush Septic Services we have not seen that to be true and any difference we have seen a septic treatment make is actually to make the septic system worse.  To understand these claims, we must first understand how your septic system works in its natural state.

Natural Septic Tank Bacteria Process

Every active septic system has bacteria in it, without using additives, and you need that bacteria to help your septic tank process waste. Beneficial bacteria, which is naturally contained in the waste you flush down your toilet, is constantly moving around in the septic system, breaking down solids, turning them into liquid waste.

After flushing waste down the toilet, these naturally-occurring anaerobic bacteria take about two days to breakdown the solids into liquids. Waste that can't be broken down sinks to the bottom as sludge while the rest floats to the top as scum or eventually goes out to the drain field as processed wastewater, having been "processed" by the bacteria in your septic tank.  When the liquids in the tank reach the drainfield, they drain safely into the yard.

As you flush more waste, the sludge level increases (amount of solids in the bottom) which is why you have  septic tanks cleaned every two years. You may need more cleanings if you have a bigger household, smaller septic tank, or large gatherings when your system is processing an increase (read: SEPTIC EMERGENCY: FLUSHABLE WIPES CAN RUIN A PARTY and BENEFITS OF RENTING PORTA POTTIES FOR YOUR NEXT EVENT before hosting an event).

Knowing how the septic system works in its natural state, for us to recommend a septic tank additive as effective, we would need to see a substantial difference in how the bacteria is processing waste. In our experience, we have not noticed a difference in a reduced amount of solids (sludge) for our customers that diligently use septic treatments.  Some actually have shown detrimental effects with either:

1. A buildup of a sawdust material on the top layer (scum layer in the diagram), and/or
2. Suspended solids. Once the scum layer is thickened with the sawdust-like material, we've seen solids suspended on the top layer.  This could lead to less sludge, but only because the solids are being pushed out to the drain field before being treated by the bacteria - which is very dangerous.

What Does the EPA Say About Septic Additives?

On the EPA.gov website:

"EPA does not make recommendations on individual septic system products. Commercially available microbiological and enzyme additives are promoted to reduce sludge and scum accumulation in septic tanks. However, these additives are not necessary for a septic system to function properly when treating domestic wastewater. Use caution when using additives in your septic system as they may decrease the performance of septic drainfields, which treat the wastewater from the septic tank. In general, do not use additives made of organic solvents or strong alkali chemicals because they pose a potential threat to soil structure and groundwater."