Interactive Calculator · 2026
Sewage Generation Calculator
Estimate the daily sewage a building generates and its peak flow. Pick a building type, enter the occupancy, and get the average sewage in KLD (kilolitres per day) plus the peak flow every STP and pump is sized around.
Water demand → average sewage → peak-day flow (KLD)
Your building
NBC 135 LPCD, full plumbing
Share of water supplied that becomes sewage — CPCB/NBC take ≈80%.
Ratio of peak-hour flow to the average — typically 2–3× for building-scale sewage.
Sewage flow at a glance
Water demand, average sewage and the peak-day flow the plant must handle — all in KLD.
The average sewage figure sets the treatment load; the peak-day flow (avg × 2.5) drives the size of pumps, screens and the inlet channel.
Convert peak-day flow to an hourly rate and you get the 4.5 m³/hr the hydraulics must clear at the busiest hour.
How this is calculated
- Water demand = occupancy × LPCD = 400 × 135 = 54,000 L/day = 54 KLD.
- Average sewage = water demand × 80% return ÷ 1000 = 43.2 KLD.
- Peak flow = average sewage × 2.5 peak factor ÷ 24 h = 4.5 m³/hr.
Indicative estimate for concept planning per NBC/CPCB norms. A detailed design must also confirm diurnal patterns, infiltration and equipment sizing — verify with a qualified consultant before procurement.
Related Guides — Deep-dive reading
Sewage Generation Calculation Explained: From Water Supply to KLD and Peak Flow
How engineers turn a building's water demand into a sewage figure — the ~80% return factor, diurnal variation, infiltration and the peak-flow multiplier — so you get an STP that is sized right, not guessed.
Sewage Treatment PlantsHow to Size an STP: A Step-by-Step Method (With Worked Example)
The complete sizing methodology for a domestic sewage treatment plant — from headcount and LPCD to sewage generation, peak flow and tank-by-tank volumes — worked end to end with an Indian apartment example.
Sewage Treatment PlantsWater Consumption Estimation for Buildings: LPCD Norms, Occupancy & End-Use Breakdown
How to estimate a building's daily water demand from its occupancy and NBC per-capita norms, break it down by end use, and turn that number into the foundation for sizing water supply, storage and sewage systems.
Sewage Treatment PlantsRelated Tools — You may also find these useful
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