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Septic Tank Size Calculator

Determine the minimum septic tank size (gallons) required for your home based on bedrooms and square footage. EPA & code compliant.

Decision summary

Septic Tank Size Calculator estimates Minimum Tank Size (Gallons) from Number of Bedrooms. Use it as a directional estimate, then verify current quotes, rates, rules, or professional advice before acting.

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Change these first: Number of Bedrooms.
Watch these outputs: Minimum Tank Size (Gallons).
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Septic Tank Size Calculator
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Configure parametersUpdated: Feb 2026
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Minimum Tank Size (Gallons)

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Assumptions used
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Number of Bedrooms

3

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Expert Analysis & Methodology

Septic Tank Size Calculator

Septic sizing is strictly regulated by local health codes, primarily based on the number of bedrooms (potential occupancy) rather than bathrooms.

General Code Requirements

  • 1-2 Bedrooms: Minimum 750 Gallons (often 1000 in modern codes).
  • 3 Bedrooms: Minimum 1000 Gallons.
  • 4 Bedrooms: Minimum 1250 Gallons.
  • 5+ Bedrooms: Add 250 gallons per additional room.

Why Bedrooms Matter

Codes assume 2 people per bedroom. A 4-bedroom house is designed for 8 people, regardless of whether 2 people actually live there. This ensures the system can handle resale capacity.

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Disclaimer

This calculator is provided for educational and informational purposes only. It does not constitute professional legal, financial, medical, or engineering advice. While we strive for accuracy, results are estimates based on the inputs provided and should not be relied upon for making significant decisions. Please consult a qualified professional (lawyer, accountant, doctor, etc.) to verify your specific situation. CalculateThis.ai disclaims any liability for damages resulting from the use of this tool.