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Septic Drainfield Size Calculator
Estimate septic drainfield area from daily flow and soil absorption.
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Estimate septic drainfield area from daily flow and soil absorption.
Septic Drainfield Size Estimator
Enter your numbers below for an instant estimate.
0
💡 Tip: Preliminary sizing only.
How It Works
Key concepts behind this calculator
1
Enter Values
Fill in each field with your own numbers.
2
Calculate
Results update as you change the inputs.
3
Review
Read the breakdown and the explanation.
4
Adjust
Change values to compare scenarios.
Quick Reference Guide
Septic Quick Guide
Typical values for reference.
| Bedrooms | Soil rate | Spare | Area m2 |
|---|---|---|---|
| 2 | 20 | – | 57.0 |
| 3 | 20 | – | 85.5 |
| 4 | 15 | – | 152.0 |
| 5 | 25 | – | 114.0 |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Common Questions
Septic Drainfield Size Calculator FAQ
Answers to common questions about this calculator.
Flow over absorption.
It gives a quick estimate of septic drainfield size from the values you enter.
No. It is a planning estimate, so check important figures with a professional or official source.
Yes. Edit any field and the result updates when you calculate.