Results and recommendations from these studies tend to vary widely. U.S. EPA literature generally recommends that septic tanks be pumped at least once every 2 to 5 years. Overall Reliability Operating without mechanical equipment, and if properly constructed and installed, septic tanks can have service lives in excess of 20 years and be considered highly reliable. Potential Environmental Impacts Table 6-1 from the EPA Design Manual for Onsite Wastewater Treatment and Disposal Systems is provided on the following page which shows typical concentrations of key parameters for effluent from residential septic tanks. A thorough site evaluation must be conducted in order to determine the appropriate level of pretreatment prior to final onsite subsurface disposal.
Septic tanks can only provide for primary levels of treatment.
Thus, some type of further treatment will need to be provided for if the soil and subsurface conditions at the site are such than ground or surface water may be adversely impacted by applying typical septic tank effluent. Energy Consumption Septic tanks do not require power consumption. Wastewater drains by gravity from the house to the tank. Costs Costs for septic tanks depend upon a variety of factors including subsurface site conditions, location of and access to the site, and the type of tank. Aesthetic Considerations Septic tanks are buried below grade, and usually do not have significant visual impacts on the site.