Sunday, September 19, 2010

Do Septic Tank Additives Work?

According to the US EPA septic system additives also sold as septic system cleaners, degraders, decomposers, deodorizers, organic digesters, or enhancers have not been demonstrated as effective and beneficial. Some of these products can do significant harm, actually interfere with treatment processes, affect biological decomposition of wastes, contribute to system clogging, and contaminate ground water. According to Washington State department of health most additives do not have a positive effect on the operation of a septic system, and can contaminate groundwater aquifers, render septic drainfields dysfunctional, and result in costly repairs to homeowners.

Washington State bans the use, sale, and distribution of additives that contain any ingredient likely to damage a septic system or contaminate groundwater. Approval for sale in Washington does not guarantee that an additive will have any positive effect; just that it is unlikely to cause harm. So, if you are bound and determined to use a septic additive no matter what, at least use one from the Washington State list. It is not likely to help, but it is also not likely to hurt.

The septic tank/soil absorption field system is the most commonly used onsite wastewater treatment system in the United States. It is relatively low in cost, has no moving parts, and requires only that you pump the tank every three to five years, maintain any moving parts and treat the system kindly and not use it for trash and chemical disposal. The septic tank is a buried, watertight container typically made of concrete, fiberglass, or polyethylene. It holds the wastewater long enough to allow solids to settle out (forming sludge) and oil and grease to float to the surface (as scum). It also allows partial decomposition of the solid fecal materials. Compartments and a T-shaped outlet in the septic tank are intended to prevent the sludge and scum from leaving the tank and traveling into the leach field area. Some newer systems have screens and filters to keep solids from entering the leach field.

The basic design of a septic tank will only work if the sludge is not too thick on the bottom and the grease and scum is not too thick on top, and if the flow to the tank is not excessive. If there is too much waste on the bottom of the tank or too much water flowing to the tank, there will not be enough time for the solids and liquids to settle out before the tank starts releasing waste. Water containing large amounts of fecal waste will be released to the drain field. Also, if there is too much grease and scum floating on top, the scum will be released to the leach field.

On first glance septic system additives may seem like a cheap way to avoid pumping a septic tank. However, additives do not eliminate the need to pump a tank and some products can damage septic systems, interfere with treatment of wastewater, and contaminate groundwater. There are three basic categories of substances sold as septic tank additives: inorganic compounds, organic solvents, and biological additives.

Inorganic additives are generally strong acids or alkalis, similar ingredients similar to the ingredients used in popular drain cleaners. These products can destroy the biological function of your septic tank, killing off all the bacteria and allowing raw sewage to flow directly into your drainfield, potentially clogging pipes and soil pores. These types of products can also corrode concrete tanks and distribution boxes, causing them to leak and potentially break apart. None of these types of substances are allowed in Washington State. In addition, you should not use these types of drain cleaners if you have a septic system because very small quantities will cause bacterial “die off.”

Enzymatic products can be beneficial if the appropriate product is used in the right quantity. There is some indication that, enzymatic products might have the ability to reduce the amount of oil and grease in the septic tank. Second, under septic tank bacterial “die-off” conditions, slight reductions in the amount of effluent solids have been achieved by using additives. Die-off conditions were observed when adding a concentration of 1.85 gallons of liquid bleach, 5.0 gallons of liquid Lysol cleaner, or 11.3 grams of Drano drain cleaner to a standard 1,000-gallon septic tank. Other factors that can cause die-off include the use of anti-bacterial agents, and, in certain cases, medications taken by household members. However, some biological additives may increase the biological activity to the point where anaerobic decomposition of solids causes the formation of methane gas. This gas could create a hazard; push solids up from the settled portion of the septic tank. Ultimately, this may lead to solids “carryover” to the soil absorption system and clogging of the drainfield. In addition one study of 48 septic tanks found no difference in sludge level between tanks that used bacterial additives and those that did not (McKenzie, 1999). So with bacterial “die-off” pumping the tank and starting again may be your best option.

Many products are sold to remedy a failing drainfield. It was proposed that hydrogen peroxide could be used to restore the infiltrative capacity of a clogged drainfield, however, research found hydrogen peroxide degrades soil structure in a drainfield, reducing its ability to treat and absorb wastewater effluent by agitating soils containing fines (clayey and loamy soil). Organic chemicals used in additives include organic solvents or surfactants that have been reformulated to make the product safer for the environment. Even at “safe” levels, napthalenes, alkanes, and benzenes easily pass through soil systems and into the groundwater, contaminating nearby wells. These substances should never be added to a septic system.

1 comment: