Do Septic Tank Additives Actually Work? Enzyme Treatment Explored

Septic tank additives are substances that are poured or flushed into septic systems to boost or restore the natural bacteria that break down the waste. They come in various forms (liquid, powder, dissolvable packets) and are marketed as a way to reduce the frequency of pump-outs, eliminate odors, keep the system running smoothly without the need for maintenance, etc. In the vast majority of cases, at least in our service area, septic tanks do not require these additives. And nationwide, millions of dollars are spent on these additives, which also happens in our service areas of Spartanburg, Greenville, Cherokee, Pickens, and Anderson Counties.

Septic tank additives belong to two categories, which affect the system very differently.

Chemical additives use acids or organic solvents in an attempt to break down waste. These are the ones most septic pros warn against since they change the pH and may kill off the native bacteria, eventually damaging the system in a way the homeowner cannot see. Old tanks are more at risk than newer ones with better engineering.

Biological additives are live organisms (bacteria, enzymes, or yeast) that try to boost the decomposition capacity of the already operating septic tank. Both enzyme-based and bacterial additives belong to this category.

Manufacturers claim their bacteria or enzymes improve waste breakdown and may even eliminate the need for pumping. Be skeptical of any product that says routine pumping is unnecessary.

You often see enzymes and bacteria paired, but they are quite different. Bacteria are living organisms that reproduce and consume waste as part of their life cycle. Enzymes are proteins that speed up specific chemical reactions, but they do not reproduce like bacteria. Their activity is limited by the conditions inside the tank, and adding them does not eliminate the accumulation of sludge and scum.

Domestic wastewater naturally introduces bacteria and other microorganisms into the tank, where an established microbial population helps break down part of the organic waste. As long as you're putting household waste into it, you're feeding the bacteria that are living in it. Adding more bacteria from a bottle is not really going to help much. Adding a bottled bacterial or enzyme product does not remove the need to monitor sludge and scum levels or pump the tank when required.

Healthy septic tanks already have bacteria in them, and they are topped off whenever you flush the toilet or drain the sink. You don't have to buy any bottled bacteria since the waste stream from your daily use is sufficient for feeding the bacteria.

So do additives really work the way the label promises? Independent research supporting the broad performance claims made for many septic additives is limited. The EPA does not recommend bacteria- or chemical-based additives for domestic wastewater systems because they are generally unnecessary and some products may harm system performance or the environment. To paraphrase Jennifer Hause, a scientist at the National Environmental Services Center at West Virginia University, these additives will not reduce sludge build-up and cannot be expected to delay pumping.

Natural biological activity breaks down part of the organic waste, but sludge and scum still accumulate over time. Additives have not been shown to eliminate that accumulation or replace pumping. Once these layers reach the service threshold, they must be physically removed by a pump truck.

Research has been consistent even as the use of additives has grown. Biological additives are unnecessary for a normally functioning domestic septic system. Their effects vary by product, and some additives may interfere with treatment or carry more suspended material into the drainfield. The tank already has enough waste inside it for bacteria to process, and adding more won't speed it up. What you spend on additives could go toward an actual pump-out instead, and that’s the step that changes the function of the tank in a meaningful way.

Maintaining a septic system over time is the key to keeping it working. Here's what actually should be done to prolong the life of a septic system.

You don't have to buy and use additives, just follow a maintenance schedule and call the professional when needed. Homeowners who do this experience system failures less often than those who don't follow the plan. There are a lot of septic treatments available, like anywhere else. But the fact is, a stressed septic field doesn’t get better from a bottle.

We had a call from a homeowner on Settle Road in Inman whose toilets gurgled every time he ran water in the kitchen. As it turned out, the septic hadn’t been pumped in 10 years. When Alex opened it, the inlet baffle was choked with a solidified mass of grease, which floats and hardens at the surface. If that homeowner had been feeding the tank with additives, nothing would have changed. The solution? Pumping and direct cleaning, which cost $400. Using additives instead of a service call would have allowed the baffle's opening to slowly narrow until it backed up into the house.

We see the same pattern repeating with old neglected systems or relatively new septic tanks that get pumped way too infrequently. An additive may make a homeowner feel like they're doing something, but it is not a substitute for regular scheduled septic tank pumping.

If your system drains slowly or you’re not sure when it was last serviced, call (864) 431-2822 so we can help. We work on septic tanks of all ages and sizes across Spartanburg, Greenville, Cherokee, Pickens, and Anderson Counties, handling septic tank pumping, septic system maintenance, and septic inspections.