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CPHEEO Calculator

Pump Power & Energy Calculator

Hydraulic, shaft, and input power + daily/annual energy + operating cost — using P = Q × H / (367 × η).

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Electricity is 50-70% of operating cost for most water utilities. Pump selection and operating-point tuning are the biggest levers for reducing this cost. This calculator takes the pump duty (Q and TDH) and the pump + motor efficiencies, and computes the full electricity picture — hydraulic kW at the pump impeller, shaft kW at the coupling, input kW drawn from the grid, and what that translates to in kWh/year and ₹/year.

The CPHEEO benchmark for urban water pumping is 0.25-0.50 kWh per m³ delivered. Efficient new systems (IE3 motor, new pump at BEP, VFD-driven) reach 0.20-0.30. Inefficient legacy systems (aged pumps, throttled valves, oversized motors) show 0.60-0.80. Knowing where you are on this scale tells you whether pump replacement is worth the capital.

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

  • Hydraulic power (kW) = Q × H / 367 — the ideal power transferred to water
  • Shaft power (kW) = hydraulic / η_pump — includes pump losses
  • Input power (kW) = shaft / η_motor — the number that shows on the electricity bill
  • Daily and annual energy (kWh)
  • Annual electricity cost (₹)
  • Specific energy (kWh/m³) — for benchmarking against CPHEEO and IWA norms

Calculator

Pump Power, Energy & Annual Cost

↓ Download Excel

Compute hydraulic, shaft, and input power + daily/annual energy + operating cost for a water-supply pump set. Formula P = Q × H / (367 × η).

Inputs
Flow Qm³/hr
Total Dynamic Headm
Static lift + friction + residual
Pump efficiency
New pump 0.80 BEP; aged 0.65
Motor efficiency
IE3 = 0.93; IE4 = 0.95
Running hours per dayhr
Electricity tariff₹/kWh
Outputs
Hydraulic power
27.25kW
P_hyd = Q × H / 367
Shaft power
36.33kW
P_shaft = P_hyd / η_pump
Input electrical power
39.07kW
P_in = P_shaft / η_motor
↪ Specify next-standard motor size (e.g., 15 → 18.5 kW)
Daily energy
781.3kWh/day
Annual energy
2,85,176kWh/yr
Annual electricity cost
22,81,406₹/yr
Specific energy
0.195kWh/m³
SE = input_kW / Q
↪ Benchmark 0.25 – 0.50 kWh/m³ for urban water pumping
CPHEEO Reference Values
Pump efficiency new0.75 – 0.88 at BEP
Motor efficiency IE30.92 – 0.95
Specific energy urban0.25 – 0.50 kWh/m³
VFD savings20–40% vs throttled fixed-speed
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

  • Q in m³/hr at the pump operating point (use the Water Demand Calculator's Max Daily to size, but for cost calcs use the average operating Q)
  • TDH = Total Dynamic Head = static lift (elevation difference) + friction losses (from Hazen-Williams calc) + residual pressure at delivery
  • Pump efficiency: 0.80 for a new pump at its Best Efficiency Point; 0.70 for an aged pump; 0.60 for an old pump running off-BEP
  • Motor efficiency: IE3 (premium) at 0.93; IE4 (super premium) at 0.95; older IE2 motors at 0.88
  • Running hours/day and electricity tariff as per your actual operation

Worked example

Worked example — mid-size urban booster pump
Q = 200 m³/hr, TDH = 50 m. Pump efficiency 75% (new pump, operating near BEP). Motor IE3 at 93%. Running 20 hours/day. Tariff ₹8/kWh. Hydraulic power = 200 × 50 / 367 = 27.3 kW. Shaft power = 27.3 / 0.75 = 36.3 kW. Input = 36.3 / 0.93 = 39.1 kW. Specify next standard motor size 45 kW (margin for starts, peaks). Daily energy = 39.1 × 20 = 782 kWh. Annual = 285,400 kWh. Cost = ₹22.8 lakh/year. Specific energy = 39.1 / 200 = 0.20 kWh/m³ — excellent, at the lower end of the CPHEEO benchmark.

Interpreting the results

Specific energy < 0.25 kWh/m³ is excellent — you're in the top quartile of Indian utilities. 0.25-0.40 is good. 0.40-0.60 has room for improvement (motor replacement, VFD, pump upgrade). > 0.60 is poor — pump/motor replacement will pay back in 2-4 years.

Annual cost is a sanity check. For a 1000 m³/hr pump running 24/7 at TDH 30, you'll see ₹1-2 crore/year in electricity. That's a significant line item — makes the case for every 1% efficiency gain being worth lakhs per year over the pump's life.

FAQs — using this calculator

When should I replace an existing pump?
When its efficiency drops below 70% at the operating point. New pumps are 75-85% efficient. Replacement typically pays back in 2-4 years via electricity savings (20-30% energy reduction). Check efficiency annually — if vibration is up, flow is down, or the motor is drawing more current than rated for the nominal duty, the pump has degraded.
Is a VFD (Variable Frequency Drive) worth the cost?
Yes, in most cases. A VFD modulates pump speed to match demand, avoiding the 'throttled valve' problem where the pump runs at full power but the valve dumps the excess. Savings 20-40% vs fixed-speed + throttle. Cost ₹2-10 lakh depending on motor size. Payback 2-4 years typical for urban applications with variable demand profile.
Why does specific energy vary so much (0.20-0.60 kWh/m³)?
Because it depends on three things: the TDH (higher = more energy), the overall efficiency (pump × motor × drive), and the operating point (pumps are efficient only within ±20% of BEP). A pump pushing water up 100 m at 50% combined efficiency uses roughly 4× the energy of one pushing 30 m at 80% efficiency. Specific energy is the single best utility benchmark for pumping performance.
How do I calculate TDH without a detailed model?
TDH = static lift (the vertical height water must rise) + friction loss (from Hazen-Williams for each pipe in the path, sum them) + residual pressure at delivery (10-20 m for a consumer network, 5-10 m for a reservoir inlet). For a booster pumping to an ESR: static lift = ESR water level − source water level; friction = rising main friction; residual = 0-5 m (pump discharges directly into the reservoir).
Should I size the motor 10-20% above calculated input power?
Yes. The calculator gives input power at the design duty. Specify the next standard motor size (e.g. calc shows 39 kW → specify 45 kW). This handles start-up surge, occasional off-duty operation, voltage variation, and ambient heat. Under-sized motors overheat and fail within 1-2 years.
How does 24×7 supply affect pump selection?
In 24×7 supply, peak factor drops from 2.7 to 1.5 — so the pump can be smaller. A city switching from intermittent (supply 2-6 hrs/day at high pump flow) to 24×7 (lower flow all day) often finds the same source + new smaller pumps + smaller pipes gives the same service. This is why AMRUT 24×7 projects often don't need new source — just better management.

Related calculators & references

Other CPHEEO Calculators

Hazen-Williams Pipe Sizing
Gives the friction loss component of TDH
Water Demand & LPCD
Distribution Pipe Check
NRW / Leakage
NRW reduction reduces pumping — direct energy saving

Indian Codes Referenced

IS 1520 — Pumps
IS 12615 — Motor Efficiency IE3/IE4

Related pages on InfraLens

CPHEEO Ch. 13 — Full pump chapter
CPHEEO Ch. 19 — O&M and Energy Management