For homes with an on-site wastewater disposal, system maintenance falls to the homeowner. Household wastewater flows into the septic tank, where the heavier solids settle on the bottom to form a sludge layer. Floatable solids, such as greases, oils and fats, collect at the surface to form a scum layer. The remaining liquids empty in to the drainfield to be treated by natural processes in the soil. Homeowners are responsible for regular tank pumping to remove solids so they do not clog the system.
It has been suggested that additives can be used in a septic system to accelerate digestion of biosolids, break up scum, improve settling of solids, or restore clogged soil. There are two distinct categories of additives: 1) chemical, including inorganic and organic compounds and 2) biological, such as yeast, bacteria, and enzymes.
Biological additives may reduce the amount of grease and effluent in the septic tank. However, these additives may increase biological activity to the point of adding extra solids to the tank. A breakdown of the scum layer in the tank by these additives is also detrimental. The scum layer holds back fats, greases and other floatables, preventing them from clogging the drainfield.Chemical additives destroy the good bacteria that break down waste in the tank and damage permeability of the soil in the drainfield. Some additives containing heavy amounts of everyday products, such as hydrogen peroxide, might not harm the bacteria in the tank but could hurt the soil in the drainfield. This would cause the purification process of wastewater in the drainfield to be less effective.
Several chemical products contain sulfuric acid, which is highly corrosive and can harm the bacteria that break down wastes. It can also cause structural damage to the tank and pipes. Additives used to reduce odor by controlling excessive anaerobic growth may contain formaldehyde, paraformaldehyde, and zinc sulfate as active ingredients. These additives act as a biocide, poisoning the system and its bacteria. The results are more frequent septic tank pumpings and a shorter system lifespan.
No septic tank additive will work better than a septic tank’s natural function and use of healthy bacteria found in human waste. Claims made that additives eliminate the need for tank pumping or restore drainfield function are unsubstantiated. No product will replace the need for tank pumping and regular maintenance.
Pumping the septic tank every 3 to 5 years, following water conservation strategies, and avoiding harsh chemicals and additives are the best way to protect the septic system. A functioning septic system is an efficient way to treat wastewater. Proper treatment of the system protects the home, water quality and our environment. For more information on septic system functioning and maintenance recommendations, contact the Shiawassee Conservation District.
This project has been funded through Michigan Department of Environmental Quality’s Nonpoint Source Program by the United States Environmental Protection Agency.