A household that is not served by a public sewer "Early Warning" Levels Inside Your trench or bed. The size and type of drainfield usually depends on a septic system for treatment The Septic Tank Septic Tank depends on the estimated daily wastewater flow and dispersal of wastewater. A well-designed, The typical septic tank is a large buried and soil conditions. installed, operated and maintained septic system rectangular or cylindrical container made of The septic tank Every new drainfield is required to have a can provide years of reliable low-cost service. concrete, fiberglass, or polyethylene. should be pumped designated 100% replacement area. It must When a septic system fails to operate Wastewater from your toilet, bath, kitchen, remain free of encroachment and damage to effectively, property damage, groundwater and when: laundry, etc. flows into the tank. Heavy solids allow a repair if needed. surface water pollution (including shellfish settle to the bottom where bacterial action • the bottom of contamination), and disease outbreaks can occur. partially decomposes them to digested sludge the scum layer Therefore, it makes good sense to understand and gases. Most of the lighter solids, including is within 3 and care for your septic system. oil and grease, rise to the top to form a scum inches (7.62 The Soil There are many different types of septic systems layer. cm) of the to fit a wide range of soil and site conditions. bottom of the The soil below the drainfield provides the final The following information will help you to outlet tee or treatment and dispersal of the septic tank understand a conventional gravity-flow septic baffle, or effluent. After the effluent has passed into the soil, most of it percolates downward and system, and keep it operating safely at the lowest possible cost. outward, eventually entering the groundwater. A • the top of the small percentage may be taken up by plants A conventional gravity-flow septic system has sludge layer is within 12 inches (30.48 cm) through their roots, or evaporates from the soil. three working parts: of the bottom of the outlet fitting. The soil filters effluent as it passes through the 1. The septic tank. Some septic tank additives on the market with pore spaces. Chemical and biological processes 2. The drainfield with its replacement area. chemicals, yeast, bacteria, or enzymes claim to treat the effluent before it reaches groundwater, or a restrictive layer, such as hardpan, bedrock, 3. The surrounding soil. improve septic tank performance or reduce the need for routine pumping. Such products are not or clay soils. These processes work best where the soil remains unsaturated, is well-drained and necessary for the proper functioning of a septic contains plenty of oxygen for several feet below tank and are not recommended. Some can cause the drainfield. Septic tanks may have one or two compartments. Two compartment tanks do a solids to carry over to the drainfield, which better job of settling solids and are required for results in early soil clogging and the need for a new systems. Tees or baffles are provided at the new drainfield. Products containing organic System Failure tank's inlet and outlet pipes. The inlet tee slows solvents contribute to groundwater pollution. Warning signs of a failure: the incoming wastes and reduces the disturbance The wastewater leaving the septic tank is a of the settled sludge. The outlet tee keeps the liquid called effluent. It has been partially • Odors, surfacing sewage, wet spots or lush solids or scum in the tank. All tanks should have treated but still contains disease-causing bacteria vegetation growth in the drainfield area accessible covers for checking the condition of and other pollutants. Discharging effluent onto • Plumbing or septic tank backups the baffles and for pumping both compartments. • the ground's surface or into surface and ground Slow draining fixtures If risers extend from the tank to or above the • Gurgling sounds in the plumbing system water is against Washington State law. ground surface, they should be secure to prevent If you notice any of these signs or if you suspect accidental entry into the tank. your septic system may be having problems, Solids that are not decomposed remain in the contact your local health agency for assistance. septic tank. If not removed by periodic pumping, The Drainfield solids will accumulate until they eventually The drainfield receives septic tank effluent. It overflow into the drainfield. Most septic tanks has a network of perforated pipes laid in need to be pumped every 3 to 5 years, depending gravelless or gravel-filled trenches (2-3 feet on the tank size and the amount and type of (.061 – 0.97 m) wide) or beds (up to 10 feet solids entering the tank. (3.05 m) wide) in the soil. Wastewater trickles out of the pipes, through the gravel layer (when present), and onto the soil on the bottom of the

disposal (not recommended) will increase 10. Check with your local health agency for the amount of solids entering the septic tank, help with system problems. Although requiring more frequent pumping. some malfunctions may require complete Caring For Your System – drainfield replacement, many problems can Understanding 5. Never flush harmful materials into the be corrected with a minimum amount of cost The Ten Essentials septic tank. Grease, cooking oils, and effort. 1. Practice water conservation. The more newspaper, paper towels, rags, coffee And Caring For Your wastewater you produce, the more grounds, feminine hygiene products, wastewater the soil must treat and dispose. diapers, flushable wipes and cigarettes Additional information is available from the Septic System By reducing and balancing your use, you can cannot easily decompose in the tank. Chemicals such as solvents, oils, paint and Washington State Department of Health at: extend the life of the drainfield, decrease the www.doh.wa.gov/septic possibility of system failure, and avoid costly pesticides are harmful to the system's proper repairs. operation and may pollute the groundwater. Septic tank additives are not recommended To reduce your water use: and are not necessary for the proper More wastewater publications are available from • Use water-saving devices. functioning of a septic tank, nor do they reduce the need for routine pumping. For your local health agency or by writing to: • Repair leaky faucets and plumbing information on the proper disposal of Washington State Department of Health fixtures. hazardous household waste, call the Recycle Wastewater Management Section • Reduce toilet reservoir volume or flow. Hotline, 1-800-RECYCLE. PO Box 47824 • Take shorter showers. Olympia, WA 98504-7824 6. Keep all runoff away from your system. • Take baths with a partially-filled tub. Water from surfaces such as roofs, • Wash only full loads of dishes and driveways, or patios should be diverted Other sources of information include: laundry. away from the septic tank and drainfield Local Health Agencies 2. Keep accurate records. Know where your area. Soil over your system should be USDA Natural Resources Conservation Service septic system is and keep a diagram of its slightly mounded to help surface water Office location. Records of its size and location runoff. WSU Cooperative Extension Office may be available at your local health 7. Protect your system from damage. Keep agency. It is also wise to keep a record of traffic such as vehicles, heavy equipment, or maintenance on the system. These records livestock off your drainfield or replacement will be helpful if problems occur, and will area. The pressure can compact the soil or be valuable to the next owner of your home. damage pipes. Before you plant a garden,

3. Inspect your system once a year. Check construct a building, or install a pool, check the sludge and scum levels inside your on the location of your system and replacement area. septic tank to assure that the layers of solids are not within the "early warning levels". 8. Landscape your system properly. Don't Also check the tank to see if the baffles or place impermeable materials over your tees are in good condition. Periodically drainfield or replacement area. Materials, For people with disabilities, this document is inspect the drainfield and downslope areas such as concrete or plastic, reduce for odors, wet spots, or surfacing sewage. If evaporation and the supply of air to the soil available on request in other formats. To submit your drainfield has inspection pipes, check for proper effluent treatment. They can also a request, please call 1-800-525-0127 them to see if there is liquid level hinder getting to the system for pumping, (TDD/TTY call 711). continually over 6 inches (15.24 cm). This inspection, or repair. Grass is the best cover WASHINGTON STATE may be an early indication of a problem. for your system. DEPARTMENT OF HEALTH 4. Pump out your septic tank when needed. 9. Never enter any septic tank. Poisonous Don't wait until you have a problem. gases or the lack of air can be fatal. Any Routine pumping can prevent failures such work to the tank should be done from the WASHINGTON STATE UNIVERSITY as clogging of the drainfield and sewage outside. back-up into the home. Use of a garbage DOH 337-086 June 2018 COOPERATIVE EXTENSION SERVICE