The National Small Flows Clearinghouse and the EPA indicate that septic system additives are typically not helpful to septic systems and in some cases may be harmful to the system or the environment. ...more A helpful septic tank additive would improve the function of the septic tank to capture settleable solids and fats, oils & grease (FOG). See Septic System Basics. Capturing settleable solids, fats, oil, and grease is the primary purpose of the septic tank. If the additive interferes with with the septic tank function, then the additive may be harming your septic system. Some additives may claim to "clean" your septic tank and may include solvents or other components to remove the solids, fats, oils, and grease from the septic tank. These pollutants may leave the septic tank and harm the drain field. A properly working septic tank is not "clean". The best way to clean your septic tank is to call a local septic tank pumper. See the Do List.
The best maintenance is routine septic tank pumping to remove the solids and fats, oils and grease (FOG). Be skeptical of any product that indicates you will “never have to pump your tank again”.
The following discussion looks at how various products may affect the septic system. There are two basic types of additives:
Biological Additives. This group includes microorganisms, bacteria, or enzymes intended to improve upon the biological degradation of wastes in the septic tank or leach field. ...more Potential impacts of biological additives are summarized below.
- Most of the biological additives are not likely to harm the system; many of these are naturally occurring in residential wastewater. Usually, these additives will not make a big difference for normal residential wastewater.
- Adding excessive amounts of these organisms to your septic tank may “super-charge” your septic tank which can lead to excessive methane production. This will generate bubbles that can stir up the settled solids, which may leave the septic tank and plug the drain field.
- If your septic tank is exposed to biocides, like poisons, bleach, cleaners, antibiotics, other medications, etc., then the biological additives may help re-establish a normal amount of biological activity and restore your septic tank to normal working order.
- Some of the biological additives claim to digest fats oils, and grease. Sounds great. If these organisms are converting the fats, oil and grease so they move more easily out of the septic tank, expect to see problems at the drain field. Why do this, when regular septic tank pumping will handle this well?
- Some septic systems are exposed to high amounts of food waste (sugars, flour, etc.) such as can be expected from a bakery, cafeteria, or restaurant. Super-charging these septic systems with biological additives (organisms) may be very helpful at digesting this extra waste. Some studies have shown improved operation of leach fields under these conditions if a septic tank aerator is also used.
Chemical Additives. These are organic and inorganic compounds that may include one (or more) various active ingredients. Be wary, read the ingredients. ...more Some active ingredients may include:
- Strong acids Don’t add these, as they can be toxic to the normal organisms in your septic tank and drain field, corrosive to the septic system components, decrease the strength and life of concrete, and pollute your groundwater environment.
- Strong alkali (like alum or caustic hydroxides) Don’t add these as they can be toxic to the normal organisms in your system and may pollute the groundwater.
- Hydrogen peroxide. There are claims that this can restore a plugged drain field and there are counter claims that any effects are temporary and may result in additional plugging of the soil under the drain field. This is not recommended for a functional system.
- Baking soda. Essentially adding carbonate ions. This would tend to buffer the wastewater solution resulting in more neutral pH. This could have benefits with regard to odor control which is sensitive to pH and dissolved oxygen concentration. See Septic Odors.
- Odor control compounds. These include formaldehydes, ammonium, and zinc sulfate as active ingredients. These are bio-cides and operate by reducing the normal bacteria growth. Not our first choice, try less aggressive odor controls first.
- Organic solvents or surfactants. These include alkenes, benzenes, naphthalenes, and ketones as active ingredients. Even at “bio-degradable” levels these may subvert the function of the septic tank to capture and hold fats, oil and grease. Dissolved fats, oil and grease that escapes the septic tank can plug the drain field. This is not recommended for a functional septic system.
Review of Specific Additives
We consider this an open topic. Show us the science of how it works and change our opinions. See our “Septic System Additives” blog. Vendors are invited to share their product testing and performance data. Property owners are also invited to share their experience with septic system additives by blogging or Contact Us.
The Massachusetts DEP has a list of septic system additives which it has reviewed and determined will not harm the septic system components, will not adversely impact the function of the septic system, nor harm the environment when used on schedule as recommended by the manufacturer. [LINK-out]