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    16. Septic Tank Savvy

    Tuesday, 17 September 2002

    by Lorraine Kingdon

    Each time you flush the toilet or wash something down the drain in your tub or sink, you create sewage. Why not simply dump this wastewater onto the ground outside the house? Three reasons: it has a strong odor, the bacteria content is high, and it contains chemicals such as nitrates that can affect the environment by leaching into the groundwater.

    In Arizona, much of this wastewater is handled by septic tanks. About 90 percent of the identified locations causing problems with the state’s water quality have onsite septic tanks for treating wastewater (effluent).

    Improperly installed or maintained septic tanks can contaminate groundwater and cause human health problems, says Kitt Farrell-Poe, Cooperative Extension water quality specialist.

    Fortunately, properly sited, designed, constructed and maintained septic systems can provide an efficient and economical wastewater treatment alternative to public sewer systems.

    Unfortunately, most homeowners just want their wastewater to go away as cheaply as possible, Farrell-Poe says.

    Basically, homeowners need education, and that’s what the Cooperative Extension and Farrell-Poe provide. The Onsite Wastewater Treatment Education program, funded through the United States Department of Agriculture, and started in La Paz, Mohave and Yavapai Counties, now operates statewide.

    The program seeks to increase the number of people willing to identify and address local water quality concerns. “Both adults and young people need to be more aware of the relationship between septic systems and drinking water. Cooperative Extension has more avenues for getting the word out than most other agencies,” Farrel-Poe says.

    Innovative teaching tools are helping adults and young people grasp these concepts. In Mohave County, for example, a septic tank model was engineered to teach owners about proper design, operation and maintenance.

    In Yavapai County, Extension developed a water testing and education program that has identified six locations exhibiting increasing nitrate levels. In a county experiencing rapid growth and increasing water supply demands, this program has opened up conversations between private well owners and local governmental agencies.

    Farrell-Poe explains that septic systems should be designed to fit individual sites, but most systems are based on the same principles: the wastewater is treated by temporarily holding it in the tank where heavy solids and lighter scum separate. The solids are decomposed by bacteria and later removed along with the lighter scum by a professional septic tank pumper. After the partially treated wastewater leaves the tank, it flows into a distribution box and then into a network of trenches. The effluent slowly seeps into the subsurface soil where it is further treated and purified.

    Alternative systems are available in areas where, for example, shallow soils can’t absorb the effluent. “There’s always an onsite solution for non-polluting wastewater treatment,” Farrell-Poe says.

    More information: Improperly installed or maintained septic tanks can contaminate groundwater and cause human health problems. Several fact sheets on inspecting, operating, maintaining, and managing septic systems are available from the website

    - Updated: September 17, 2002

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