Interactive Planner · 2026
Apartment STP Planner
Plan a sewage treatment plant for an apartment complex. Enter the number of flats and occupancy, and get the recommended STP capacity in KLD (kilolitres per day) — the number every housing-society STP design starts from.
Water demand → sewage generated → installed STP capacity
Your apartment complex
Litres per capita per day — NBC takes 135 LPCD for residential occupancy.
Share of water supplied that becomes sewage — CPCB/NBC take ≈80%.
Demand → sewage → STP capacity
Fresh-water demand, the sewage it generates, and the installed STP size — all in KLD.
Your 100 flats house about 400 residents, drawing ≈54 KLD of fresh water. Around 80% returns as sewage (≈43.2 KLD), and a 15% design margin lifts the installed plant to 50 KLD.
Set aside roughly 30 m² for the plant and equipment room, and plan for MBBR or SBR at this scale.
How this works
- Population = flats × persons = 100 × 4 = 400 residents.
- Water demand = population × LPCD = 400 × 135 = 54 KLD.
- Sewage generated = water demand × 80% return = 43.2 KLD.
- STP capacity = sewage × 1.15 (15% margin), rounded up = 50 KLD.
- Space ≈ capacity × 0.6 = 30 m²; technology follows the plant size band (MBBR or SBR).
Indicative planning per NBC/CPCB norms. Detailed design must also fix peak factor, tank volumes and equipment — confirm with a qualified consultant before procurement.
Related Guides — Deep-dive reading
Apartment STP Planning Guide: Sizing, Space & Compliance
How to plan a sewage treatment plant for an apartment complex — sizing it from occupancy, choosing the right technology, finding space for it, plumbing it for reuse, and keeping it compliant and running for years.
Sewage Treatment PlantsSTP for IT Parks & Campuses: Central-Plant Design, Reuse & Redundancy Guide
How to plan a campus-scale sewage treatment plant for a multi-building IT park in India — the daytime flow pattern, the right technology, sizing for a central plant, and a reuse network feeding landscape, flushing and cooling towers.
Sewage Treatment PlantsSTP for Hotels: High Per-Guest Loads, FOG & Water Reuse Explained
Why hotel wastewater is heavier and swingier than an apartment's, which STP technology (MBBR vs MBR) actually fits, how to size for peak occupancy, and where the treated water pays for itself — in laundry, cooling and landscape.
Sewage Treatment PlantsRelated Tools — You may also find these useful
Daily Water Consumption Calculator
Estimate a building's total daily water consumption in KLD from occupancy and LPCD, with the end-use split across bathing, flushing, washing, kitchen and drinking.
Water CalculatorPopulation Equivalent (PE) Calculator
Convert an organic pollution load into Population Equivalent from flow and BOD concentration — the BOD load in kg/day and equivalent number of people.
STP CalculatorSewage Generation Calculator
Estimate the daily sewage a building generates and its peak flow in KLD from occupancy, LPCD, sewage return factor and peak factor.
STP Calculator