| Primary value | 135 LPCD (L per capita per day (sewage = 80% of water demand)) |
| Applies to | Apartment buildings, gated communities and resorts that need an in-house STP · Group housing schemes ≥ 20,000 sqm built-up (mandatory in most Indian cities) · Hotels, hospitals and mixed-use developments |
| Exceptions | Cities ≥ 1 million population → 150 LPCD water demand · ≈ 135 LPCD sewage |
| Cities < 1 million population → 135 LPCD water · ≈ 110 LPCD sewage | |
| Hostel / student housing → 120 LPCD | |
| Hotels (per occupied bed) → 180 – 220 LPCD | |
| Sewage flow vs water demand → ≈ 80% | |
| Peak factor for sizing → 2.5 – 3.0× average | |
| Measured as | Average daily sewage flow per resident in litres = water supply rate × 80%. Multiply by population to get average daily flow; multiply by peak factor for sizing the STP units. |
| Source | CPHEEO Manual — Sewerage Section 2.5 ✓ Verified |
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STP capacity drives the entire utility footprint of a township — pump rooms, treatment tanks, sludge handling, even land set aside for soak fields. 135 LPCD is the CPHEEO benchmark for a Tier-1 Indian city; smaller cities and standalone projects often size for less and end up flooding their plant within 3 years.
Township STPs are sized at 135 LPCD × 1000 occupants × 1.25 buffer = ~170 KLD plant for a 1000-resident community. Fancy MBR and SBR plants are commonly oversized by 30% to handle peak load events without bypass. Smaller buildings (< 100 occupants) typically pool with neighbours into a shared CETP.