Septic System Additives

There are a number of products on the market that claim to improve the performance of septic systems. These claims have been promoted through advertising, septic tank pumpers, and mass mailings.

An article issued in October 1988 by the Department of Social and Health Services summarizes a number of studies and references dealing with septic tank additives. Based on these and other studies in 1993 the Washington State Legislature found that “most additives do not have a positive effect on the operation of on-site systems, and can contaminate groundwater aquifers, render septic drainfields dysfunctional and result in costly repairs to homeowners.” A law was then passed that banned the use, sale and distribution of additives within the state unless an additive has been specifically approved by the Department of Health as not having an adverse effect on public health or water quality. WAC 246-273, effective January 1996, details the review procedure.

Septic additives are available in a number of different forms:

• Bacteria
• Enzymes
• AcidsOrganic Solvents
• Alkalis

The different kinds of additives work in different ways.

Bacterial cultures can interfere with the settling of solids in the tank. The suspended material can then move into the drainfield and cause plugging of the soil. Drainfield replacement may become necessary.

Acids and alkalis can impact the normal and essential biological activity in both the tank and drainfield. This desirable biological activity purifies wastewater by breaking down waste particles, inactivating dangerous disease vectors, and converting nutrients which can affect drinking water and streams.

Enzymes can help dissolve greases but can result in excessive activity in the drainfield. The “clogging mat” which results can irreversibly damage the drainfield.

Organic solvents such as tetrachloro-ethylene, methylene chloride, and trichloroethane are toxic or carcinogenic. They may dissolve greases but can result in contamination to groundwater and drinking water systems.

SYSTEM MAINTENANCE

Unlike septic system additives, there has been considerable research on system maintenance. These studies have shown beneficial results from on-going maintenance.

Pumping
One of the most important maintenance steps is pumping of the tank. The tank acts as a settling basin for waste solids, which accumulate at the bottom of the tank. Pumping these solids out of the tank approximately every 5 years will prevent them from migrating into the drainfield where they clog soil pores.

Water Conservation
Reduction of the wastewater which enters the system is another important element of system maintenance. Watersaving fixtures and appliances can enable even marginal systems to function adequately. Water can also enter the system from stormwater runoff and groundwater seeps. The use of roof gutters, downspouts, and curtain drains to divert stormwater away from the drainfield will prevent overloading of the system.

Waste Reduction
The greater the waste introduced into the system, the greater the load on the tank and drainfield. Garbage disposals can dramatically increase this load and are a common cause of system failure and should not be used.

Protection from Mechanical Damage
The drainfield is particularly susceptible to damage from vehicular traffic and mechanical disruption. No construction or vehicular traffic should be permitted in the vicinity of the drainfield or reserve area.

Maintain Landscaping
Keep large shrubs and trees away from the drainfield area, roots can cause damage to the system. Don’t place impermeable materials over the drainfield, they reduce evaporation and the supply of oxygen necessary for proper treatment.

NEED HELP?

No-cost assistance is available in the following ways:

Information on financial assistance which may be available to property owners to repair or upgrade their on-site sewage systems.

General information on septic systems and water quality.

Workshops for understanding, operating and maintaining your on-site sewage system.

FOR MORE INFORMATION CONTACT:

Jefferson County Public Health
Environmental Health Division
615 Sheridan
Port Townsend WA 98368
360.385.9444

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