Important information for owners of septic and onsite treatment systems

Items to Avoid

The following guidance is a collaborative effort of wastwater professionals within the National Onsite Wastewater Recycling Association(NOWRA). The purpose is to identify common issues that can cause problems with the operations of newer onsite treatment and traditional septic systems. Many operational problems exist today because owners are unaware of the results of daily practices to these systems.

NOWRA's goal is to ensure that owners are educated and informed about the safe practices for teir treatment systems in order to avoid costly repairs and to protect groundwater quality. The items listed below are known to have caused failures of septic and onsite treatment systems and must be considered if waste generated by/from a particular site will contain them in excessive quantities. This means that tanks must be pumped more frequently. Since "excessive" is a subjective word, it is highly recommended by NOWRA that you share any concerns with a Wastewater Profesional to come up with a treatment strategy for your particular needs.

Inert Materials
Plastic, rubber, scouring pads dental floss, kitty litter, cigarette filters, bandages, hair, mop strings, lint, rags cloth, and towels do not degrade in an onsite treatment system. Inert materials build up solids and lead to system malfunction, clogging or increased pump out frequency.

Paper Products
Disposible diapers, paper towels, facial tissues, baby wipes, lotioned, scented or quilted toilet tissue, do not dissolve readily in an onsite treatment system. Also, excessive amounts of toilet tissue do not easily decompose, and can lead to system malfunctions, back up or increased pump-out frequency.

Food Wastes
Do not put animal fats and bones, grease, coffee grounds, citrus and melon rinds, corncobs, or eggshells, down the sink. Garbage disposal use should be limited to waste that cannot be scooped out and thrown in the trash. Spoiled dairy products and yeasts from home brewery or baking may cause excessive growth of microbes that do not degrade sewage.

Household Products
Do not flush female sanitary products, cotton balls or swabs, or condoms into the system. Antimicrobial soaps and automatic disinfection tablets (blue, clear or otherwise) may kill the organisms needed to consume waste.

Medications/Ailments
Normal use of over-the-counter medications will not affect the performance of onsite systems; however, do not flush expired medicines/antibiotics into an onsite treatment system. Some prescription medications are known to cause biological disruption. Diseases or conditions which can affect septic system function include bulimia, severe infections (including AIDS), cancer, chronic diarrhea, intestinal/colon by-pass, or other gastrointestinal conditions.

Commercial Additives
Both the U.S. Environmental Protection Agency and the Small Flows Clearing House report that there is not evidence to support the use of additives with normally functioning onsite treatment systems. Some septic tank additives have been shown to do more harm than good. A normally functioning system should not require additives.

Chemicals and Toxins
The following materials kill the microbes necessary for the biological treatment to occur: paint, paint thinner, solvents, volatile substances, drain cleaners, automotive fluids, fuels, pesticides, herbicides, fertilizers, metals, disinfectants, sanitizers, bleach, mop water, floor stripping wastes, excessive use of household chemicals and backwash from water softner regeneration.

Laundry Practices
Because onsite systems process water as it enters the system, laundry should be spread out over the week and not run all at one time. Excessive use of detergents, especially those containing bleach, can affect system performance. Liquid detergents are recommended over powder. Fabric softner sheets are recommended over liquid softners, bleach should be used sparingly and at half the rate indicated on the container.

Clear Water Waste
Excessive flows from A/C discharge lines, floor drains, gutters, whole house water treatment systems and sump pumps can increase the flow to your treatment system. These flows can at least disrupt, if not destroy, your treatment process.


Remember- if you have additional questions, consult your wastewater professional.