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Water Demand & LPCD Calculator

Convert design population into average, maximum, and peak flows — with fire demand and UFW allowance — per CPHEEO and BIS 1172:2012.

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This is the most-run calculator in Indian water supply engineering. Every DPR, every AMRUT upgrade, every JJM scheme starts by converting design population into MLD demand. The LPCD standard applied governs every downstream decision — pipe diameter, treatment capacity, pumping energy, reservoir volume, tariff.

The CPHEEO values remain the governing standard: 135 LPCD for urban areas with underground sewerage, 70 LPCD urban without sewerage, 55 LPCD rural (upgraded from the older 40 LPCD figure to align with BIS 1172:2012 and the Jal Jeevan Mission). Metros (Delhi, Mumbai, Chennai, Bangalore, Hyderabad, Kolkata) routinely design at 150-200 LPCD to reflect higher standards of living.

Peak factors convert average demand into the design flows that actually govern sizing: raw water intake needs 1.0 × average; treatment plant 1.1-1.2 × average; clear-water pumping 1.5 × average; distribution 2.5-3.0 × average (intermittent supply) or 1.3-1.8 × average (24×7 supply under JJM/AMRUT targets).

Based on the CPHEEO Manual on Water Supply and Treatment, published by the Central Public Health and Environmental Engineering Organisation, Ministry of Housing and Urban Affairs, Government of India.

What this calculator computes

  • Average daily demand (m³/day and MLD) — the baseline
  • Maximum daily demand — governs raw water intake and main transmission sizing
  • Maximum hourly demand — governs distribution pipe network
  • Fire demand via Kuichling's formula: Q = 3182 × √(P/1000) L/min
  • Design flow including UFW allowance and fire storage

Calculator

Water Demand, LPCD, and Peak Factors

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Compute average daily, max daily, peak hour, and design flow for the 30-year horizon. Includes fire demand (Kuichling) and UFW allowance per CPHEEO Chapter 3.

Inputs
Design populationpersons
Per-capita supplyLPCD
135 urban+sewer, 70 urban, 55 rural (JJM/BIS 1172:2012)
Max day / avg day factor×
Max hour / avg hour factor×
2.5-3.0 intermittent; 1.3-1.8 for 24×7 supply
UFW (NRW) allowance%
Outputs
Average daily demand
13,500m³/day
Q = Population × LPCD / 1000
Average daily demand
13.50MLD
Maximum daily demand
24,300m³/day
Q_max_day = factor × Q_avg
↪ For source, raw-water main sizing
Maximum hourly demand
1,518.75m³/hr
Q_peak_hr = pfHr × (Q_avg / 24)
↪ For distribution pipe sizing
Fire demand (Kuichling)
31,820L/min
Q_fire = 3182 × √(P/1000)
Design flow (distribution, with UFW + Fire)
35,581.8m³/day
Q_design = Q_max_day × (1 + UFW%) + Q_fire × 4 hr
CPHEEO Reference Values
LPCD urban+sewer135
LPCD urban no-sewer70
LPCD rural (JJM)55
Max-day factor1.8
Peak-hour factor2.5–3.0 (intermittent), 1.3–1.8 (24×7)
UFW design allowance15% (AMRUT/JJM target <20% actual)
Download the Excel version to keep a local copy with live formulas — change inputs in the sheet and outputs recompute automatically.

How to use the inputs

  • Enter the design population from your 30-year forecast (use the Population Forecasting Calculator)
  • Pick LPCD: 135 for urban + sewerage (AMRUT standard); 70 urban without sewerage; 55 for rural JJM schemes
  • Leave max-day factor at 1.8 (CPHEEO default) unless your project has specific guidance otherwise
  • Peak hour factor: 2.7 for intermittent supply (most Indian cities); 1.5-1.8 if designing for 24×7 supply
  • UFW allowance: 15% for design; AMRUT/JJM targets are < 20% actual, but don't design tighter than 15%

Worked example

Worked example — 100,000 population AMRUT city
Population 100,000, LPCD 135 (with sewerage). Average daily = 100,000 × 135 / 1000 = 13,500 m³/day = 13.5 MLD. Maximum daily (× 1.8) = 24.3 MLD — sizes the raw water intake and transmission. Maximum hourly = 13.5 / 24 × 2.7 = 1,520 m³/hr — sizes the distribution mains. Fire demand (Kuichling) = 3182 × √100 = 31,820 L/min = 1,910 m³/hr, delivered for 4 hours = 7,640 m³ fire storage in the reservoir. Design flow for distribution = 24.3 × 1.15 (UFW) + fire = 28 + 7.6 = 35.6 MLD peak day.

Interpreting the results

Use 'Maximum daily demand' to size the raw water intake, transmission main, and treatment plant. Use 'Maximum hourly demand' to size distribution mains and service reservoirs. The 'Design flow including UFW + fire' is the conservative capacity check for critical infrastructure.

If you're transitioning an intermittent system to 24×7, re-run with peak factor 1.5 — you'll find the existing network carries more headroom than you thought, because peak factor drops from 2.7 to 1.5 as demand spreads across the day. This is often the cheapest way to 'add capacity' to an existing AMRUT city.

FAQs — using this calculator

Why is the rural LPCD 55 and not 40?
BIS 1172:2012 upgraded the rural standard from 40 LPCD to 55 LPCD to reflect modern standards of living (washing machines, better toilets, higher hygiene expectations). Jal Jeevan Mission adopted 55 LPCD as the design basis. The older 40 LPCD figure in earlier CPHEEO editions is obsolete for new schemes.
When should I use 150-200 LPCD instead of 135?
Metros with high standards of living — Delhi, Mumbai, Chennai, Bangalore, Hyderabad, Kolkata — and specific high-income enclaves within tier-2 cities. Mumbai currently supplies ≈240 LPCD. Justify any value above 135 with per-capita consumption data from an existing similar city.
Is fire demand always needed?
For any scheme serving population > 50,000 per CPHEEO. For smaller populations, local fire services may use tankers, and dedicated fire storage may not be justified. Check with the municipal fire service during DPR. For commercial/industrial zones with high-rise buildings, fire demand can dominate peak flow — compute separately.
Why does the design flow include both UFW AND fire?
Because both occur simultaneously at peak conditions: UFW (leakage) is always happening, and fire is a design emergency that must be met even during peak demand. Distribution mains must carry max daily × (1 + UFW%) + fire-flow for the fire-duty section. Sizing for just one underestimates the pipe diameter.
The 24×7 peak factor of 1.5 looks suspiciously low. Is this realistic?
Yes — when consumers have water 24 hours, they spread their usage (no need to fill overhead tanks in a 2-hour supply window). The peak drops from 2.7 to 1.3-1.8. This is why AMRUT 24×7 projects report 'new capacity' being added simply by flattening the demand curve — the source and WTP are the same, but the distribution network handles more people because peak compresses less.
How does UFW allowance compare to actual UFW?
Design allowance = 15% per CPHEEO. Actual Indian urban UFW averages 35-45%. AMRUT/JJM programs target bringing actual below 20%. You design at 15% and implement NRW reduction programs (DMAs, pressure management, leak detection — see the NRW Calculator) to push actual toward 15%.

Related calculators & references

Other CPHEEO Calculators

Population Forecasting
Upstream input to this calculator
Service Reservoir Sizing
Downstream: size ESR from daily demand
Hazen-Williams Pipe Sizing
Size transmission main from max daily
Pump Power Calculator
Pump selection from flow + head
NRW / Leakage Calculator
Close the loop on UFW reduction
Rural JJM Scheme Sizer
All-in-one for rural schemes

Indian Codes Referenced

IS 1172 — Rural Water Supply 55 LPCD
IS 10500 — Drinking Water Quality

Related pages on InfraLens

CPHEEO Ch. 3 — Full demand chapter
LPCD tables, peak factors, all clauses
All CPHEEO chapters
Handbook — Reference Tables