1. What is Septic Tank Sizing Calculation?

Septic tank sizing calculation determines the appropriate capacity of a septic tank based on daily wastewater flow and required retention time. Proper sizing ensures efficient treatment and prevents system failure.

2. How Does the Calculator Work?

The calculator uses the septic tank sizing formula:

Where:

• \( Daily Flow \) — Average daily wastewater flow in gallons per day (gpd)
• \( Retention Days \) — Required retention time (2-3 days)

Explanation: The formula ensures sufficient capacity for proper settling, digestion, and treatment of wastewater before effluent leaves the tank.

3. Importance of Proper Sizing

Details: Correct septic tank sizing is crucial for effective wastewater treatment, preventing backups, protecting drain fields, and complying with local regulations.

4. Using the Calculator

Tips: Enter daily flow in gallons per day (gpd) and select appropriate retention days (typically 2-3 days based on local codes and usage patterns).

5. Frequently Asked Questions (FAQ)

Q1: Why is 2-3 days retention time used?
A: This allows sufficient time for solids to settle and for anaerobic digestion to occur, ensuring proper treatment before effluent reaches the drain field.

Q2: How do I estimate daily flow?
A: Daily flow can be estimated based on number of bedrooms, occupants, or water usage records. Typical residential use is 50-100 gallons per person per day.

Q3: What factors affect retention time selection?
A: Local regulations, soil conditions, household size, and wastewater characteristics influence whether 2 or 3 days retention is appropriate.

Q4: Are there minimum size requirements?
A: Most jurisdictions have minimum size requirements (often 1000 gallons for residential use) regardless of calculated size.

Q5: Should I consider future expansion?
A: Yes, it's recommended to size for potential future needs, especially if home additions or increased occupancy are planned.