Septic Tank Size Calculator
Septic Tank Size
Formula
Tank Size = max(Code Minimum, Daily Flow × 2) | Daily Flow = Occupants × 75 gal × Usage Factor
Frequently Asked Questions
What size septic tank do I need?
Most codes require: 1-2 bedrooms: 750-1,000 gallons. 3 bedrooms: 1,000 gallons. 4 bedrooms: 1,250 gallons. 5+ bedrooms: 1,500+ gallons. A complete septic system (tank + drain field) typically costs $5,000-$20,000 depending on soil conditions and system type.
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