Septic tank size calculator
Estimate the capacity and approximate size of a household septic tank from the number of users, on IS 2470 lines.
How it works
We size the liquid capacity from the number of users with a ~24-hour detention, then suggest a length × width at a ~1 m liquid depth.
- Indicative only — IS 2470 has detailed tables.
- Pair it with a properly sized soak pit.
Septic Tank Calculator FAQ
What size septic tank for 5 people?›
Roughly a 2,000-litre liquid capacity, about 2 × 1 × 1.3 m — confirm with IS 2470 and your engineer.
Do I need a soak pit?›
Yes — the septic tank's outflow needs a soak pit or dispersion trench sized for your soil.