The frequency of pumping depends on several factors:

1. capacity of the septic tank
2. volume of wastewater
3. amount of solids in wastewater

The following table lists estimated pumping frequency according to septic tank capacity and household size. The frequencies were calculated to provide a minimum of 24 hours of wastewater retention assuming 50 percent digestion of the retained solids. These numbers are for estimation purposes only - every system and situation is different and pumping may be required more or less often than indicated. If you are in doubt, contact your local septic system professional.

Estimated septic tank pumping frequencies in years for full-time residences:

         (for year-round residences)

 Tank           Household size (number of people)
 size  1    2    3    4    5    6    7    8    9   10
(gal)
      ---------------Years between pumping--------------
500*  5.8  2.6  1.5  1.0  0.7  0.4  0.3  0.2  0.1   -
750*  9.1  4.2  2.6  1.8  1.3  1.0  0.7  0.6  0.4  0.3
900  11.0  5.2  3.3  2.3  1.7  1.3  1.0  0.8  0.7  0.5
1000 12.4  5.9  3.7  2.6  2.0  1.5  1.2  1.0  0.8  0.7
1250 15.6  7.5  4.8  3.4  2.6  2.0  1.7  1.4  1.2  1.0
1500 18.9  9.1  5.9  4.2  3.3  2.6  2.1  1.8  1.5  1.3
1750 22.1 10.7  6.9  5.0  3.9  3.1  2.6  2.2  1.9  1.6
2000 25.4 12.4  8.0  5.9  4.5  3.7  3.1  2.6  2.2  2.0
2250 28.6 14.0  9.1  6.7  5.2  4.2  3.5  3.0  2.6  2.3
2500 3E.9 15.6 10.2  7.5  5.9  4.8  4.0  3.5  3.0  2.6