Septic Tank Design Calculator
Septic Tank Design Calculator
(BNBC 2020 + ACI Reference)
| Input Parameters | |
|---|---|
| Number of Users | |
| Wastewater Generation (L/Person/Day) – BNBC 2020: 100–150 | |
| Detention Time (Days) – BNBC 2020: 1–2 Days | |
| Sludge Storage (L/Person/Year) – BNBC 2020: 40 | |
| Cleaning Interval (Years) | |
| Adopted Liquid Depth (m) – Min 1.2m (BNBC 2020) | |
| Freeboard (m) – BNBC 2020: 0.30m | |
| Calculated Volume | |
| Total Volume (m³) | - |
| Calculated Internal Dimensions | |
| Width B (m) | - |
| Length L (m) = 2.5 × B | - |
| Total Depth (Liquid + Freeboard) | - |
| 1st Chamber Length (2/3) | - |
| 2nd Chamber Length (1/3) | - |
BNBC 2020 Key Requirements
- Detention Time: 1–2 Days
- Minimum Liquid Depth: 1.2 m
- Freeboard: 300 mm
- Length = 2 to 3 × Width (2.5 adopted)
- Minimum 2 Chambers (2/3 + 1/3)
- Minimum Width: 0.75 m
ACI 318 Structural Notes
- Concrete Strength ≥ 20 MPa
- Wall Thickness: 125–150 mm minimum
- Provide reinforcement for soil & water pressure
- Provide waterproofing coating