Agricultural and Biosystems Engineering
The key to preventing on-site wastewater treatment system problems is to follow a regular septic tank pumping schedule — every three to five years Septic tanks trap solids and floating materials and prevent them from entering the soil treatment field. After anaerobic bacterial action, these materials are converted into sludge and floating scum. Solids or scum that escape a septic tank plug soil pores and slow the soil's acceptance rates of septic tank effluent and cause on-site systems to backup. Pumping septic tanks after backup problems occur only provides a short-term remedy, usually 2-3 days, until the tank refills with wastewater.
Derickson, Russell, "Periodic Maintenance for On-Site Wastewater Treatment Systems" (2002). SDSU Extension Extra Archives. 27.