Take Septic Additives Off the Shopping List

If you have a septic system, you have probably used, or considered using, a septic additive. The advertisements make them sound like a cheap and natural way to maintain your tank and system. For just a few dollars, you can remove more sludge from your tank by flushing their additives down your toilet. But do they really work as advertised? Are they worth the money? Can they help with your failing septic system?

The simple answer is no. Your septic tank already has all the bacteria it needs to work properly, as long as you routinely pump it every 3-5 years.

MOWPA_Filled DBox

If you haven’t been routinely pumping your septic tank every 3-5 years, the sludge could be pushed into parts of the system that are only meant for wastewater, like this distribution box. If a septic professional has told you that your system is failing, we recommend getting a second opinion and estimate, not septic additives. No amount of additives can help address this issue. (Photo courtesy of the Maryland Onsite Wastewater Professionals Association.)

But couldn’t the additives still help?

Well, no. Most septic tank additives contain beneficial bacteria or enzymes, or a combination of both, that the companies claim will help digest or breakdown the sludge (or waste solids) in your tank. But one of the main purposes of your tank is to collect human waste, which is loaded with the necessary bacteria species to digest the waste solids. Studies have shown that a typical, 1,000-gallon septic tank contains an average population of 3.64 billion to 3.64 trillion bacteria cells per gallon. Additives claim to add up to several billion bacteria cells per treatment. Though that sounds like a lot, it would only account for 0.1 – 1% of what is already present in your tank.

Couldn’t a little still go a long way?

The answer is still no. Numerous research studies have tested the effect that additives have on septic sludge volume and water quality. Some studies used lab-based, batch reactors (essentially, small septic tank simulations) and others tested numerous home septic tanks.  All of the studies concluded that additives did not show any significant sludge reduction or increase in bacterial populations. One additive actually introduced a negative effect by increasing total suspended solids (the small particles in liquid waste) that could impede the normal flow of the drain field. Studies also suggested that additives should not be used as a substitute for, or as a means to reduce, septic tank pumping frequency.

Don’t Forget The Bottom Line!

Septic additives cost approximately $4-10/month, or $50-120/year. One of the most important maintenance tasks to ensure a properly functioning septic systems is to routinely pump your septic tank.  The University of Maryland Extension recommends that you pump your tank every three to five years. The national average for pumping a septic tank is $380. That means that the expense of additives would cover the cost of routinely pumping your tank.

So the bottom line on septic tank additives is that they aren’t worth the money. Just call your local pumper and schedule a pump-out.

This post was co-written by Daphne.

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