4.1 Septic Tank Treatment Efficiency

The following information provides guidance on the effectiveness of septic tank treatment of domestic wastewater. Table 3 provides the minimum frequency for septic tank pumping as a function of the household population. If garage grinders are used divide the recommended pumping frequency by a factor of approximately two. Therefore, a 3 person family with a 1000 gallon septic tank with no garbage grinder should pump the tank at a frequency of at least 3.7 years. If a garbage grinder is used the pumping frequency should be every two years. Table 4 is a summary of septic tank effluent quality data and approximate percent reductions assuming domestic wastewater.