Recommended septic tank capacity
- 1-2 bedroom house = 750 gallons
- 3 bedroom house = 1000 gallons
- 4 bedroom house = 1200 gallons
Size and dimensions
The average septic tank requires a space about 10 ft. by 10 ft. The disposal (or drain) field should be 30 ft. by 50 ft. or larger, with an additional area of similar size held in reserve in case of drain field failure. The drain field must have 4 ft. of good native soil from the surface to the water table or hardpan and a minimum of 2 ft. vertical separation from trench bottom to the water table or impervious material such as hardpan.
