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Screening-stage estimator for water treatment plant CAPEX/OPEX, electricity use, modular unit count, and plot footprint based on water source, end use, and flow.
Used to pick screening defaults for specific energy use and reference CAPEX.
Used to adjust treatment stringency defaults (CAPEX and chemicals).
Nameplate treated water output at design conditions.
min 50 · max 20000 · step 50 · m3/day
Fraction of the year the plant operates at average design throughput (accounts for downtime and partial operation).
Blended power price paid by the plant (energy + supply where appropriate).
Used for annualizing CAPEX via capital recovery factor (CRF).
Economic life used for CRF-based annualization.
Levelized cost of treated water
Total annual cost divided by annual treated volume
Installed plant cost (installed CAPEX)
Equipment purchase × installation factor; excludes owner costs unless embedded
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Flows & footprints
Annual treated water production
Net production based on capacity factor (utilization)
Average electrical demand at load
Annual kWh divided by operating hours
Number of modular treatment trains
Rounded up to meet design capacity
Equalization/buffer tank volume
Simple hours-of-storage basis
Equalization tank diameter (approx.)
Assumes vertical cylinder and fixed liquid height
Estimated plot space requirement
Process footprint × integration factor
Equipment cost: Main treatment (core process skids)
Allocated fraction of equipment purchase CAPEX
Equipment cost: Pretreatment
Allocated fraction of equipment purchase CAPEX
Equipment cost: Post-treatment & disinfection
Allocated fraction of equipment purchase CAPEX
Equipment cost: Controls, electrical & instrumentation
Allocated fraction of equipment purchase CAPEX
Equipment purchase cost (EPC excl.)
Purchase cost only; excludes installation and indirects
Equipment cost: Intake & raw water pumping
Allocated fraction of equipment purchase CAPEX
Installed plant cost (installed CAPEX)
Equipment purchase × installation factor; excludes owner costs unless embedded
Annual fixed O&M cost
Maintenance/labor/overheads proxy (excludes electricity, chemicals, replacements)
Annual membrane/media replacement cost
Variable OPEX as fraction of main-treatment equipment
Annual chemicals & consumables cost
Variable OPEX scaled by treated volume
Calculator context
This calculator provides a pre-feasibility (screening) estimate of water treatment plant costs (CAPEX/OPEX), power consumption, annual treated water production, and plot-space footprint using only inputs a business developer typically knows early: water source, intended use, design flow, electricity price, capacity factor, and financing assumptions. It is intended for rapid option screening and order-of-magnitude comparisons for Technology: other treatment configurations.
Methodology follows common early-phase practices used across water infrastructure and energy project screening: (i) power-law scaling for equipment cost with capacity, (ii) installed-cost factors (Lang-factor style) to move from equipment purchase to installed plant cost, and (iii) annualization via CRF to compute a levelized cost per unit output. Default reference values are informed by publicly available synthesis sources and cost-method conventions (e.g., IRENA/IEA costing frameworks, NREL desalination and water-treatment energy intensities, and sector handbooks such as AWWA/WEF guidance).
Key steps and equations (variables defined in-line):
Capacity & utilization
Energy use with part-load penalty
Costing (screening scale-up + breakdown)
Annualization & levelized cost
45 assumptions used in the calculations
Prevents division-by-zero and unstable behavior at extreme/invalid inputs.
Used to convert capacity factor into annual operating hours.
Market range 8760
Used where daily capacity is the base unit.
Converts m3/day to m3/h for load-hour calculations.
Market range 24
Converts kWh to MWh for reporting and costing.
Market range 1000
Tank area/diameter geometry.
Market range 3.14159
Used in cylinder diameter back-calculation from volume.
Market range 4
Defines the anchor point for specific CAPEX and O&M scaling.
Captures decreasing specific CAPEX with capacity at screening level.
Prevents unrealistically low specific CAPEX when scaling to very large plants.
Prevents unrealistically high specific CAPEX for very small plants or extreme scaling.
Screening reference for conventional treatment with moderate pretreatment requirements.
Often lower solids/turbidity reduces pretreatment scope at screening level.
Higher-pressure desalination trains and pretreatment increase equipment cost.
Higher polishing/disinfection and compliance requirements increase CAPEX.
Baseline multiplier for general industrial utility/process water at screening level.
Often less stringent than potable, reducing polishing scope.
Approximates installation labor, piping, electrical, civil integration, and contractor overheads.
Represents labor/maintenance/overheads excluding explicitly modeled variable OPEX items.
Allows fixed O&M fraction to decrease mildly with scale.
Prevents unrealistically low fixed O&M at large scale.
Caps fixed O&M fraction for very small plants / extreme scaling.
Captures reduced efficiency at lower utilization (auxiliaries, cycling, suboptimal operation).
Prevents excessive penalty escalation at low capacity factor.
Represents typical pumping + filtration/disinfection energy at screening level.
Often lower solids load; energy dominated by pumping and basic treatment.
Represents RO/high-pressure dominated energy use at screening level.
Adds modest energy for additional polishing/disinfection and tighter process control.
Neutral baseline at screening stage.
Lower polishing needs can reduce treatment energy at screening level.
Coagulants, pH adjustment, disinfectant, minor consumables at screening level.
Moderate chemical consumption for general industrial water conditioning.
Lower chemical demand at screening level for less stringent quality targets.
Captures periodic replacement averaged as an annual fraction of main-treatment equipment cost.
Provides sub-system purchase cost breakdown consistent with a typical modular plant.
Represents screens/DAF/filters/UF front-end depending on source quality.
Core process skids often dominate purchase cost in modular plants.
Includes remineralization/pH adjustment/disinfection and finishing.
Provides a screening share for PLC/SCADA/instrumentation and MCC components included in purchase scope.
Defines how many parallel units are required for the plant design flow.
Used to estimate process area and plot space at screening level.
Provides buffering for feed variability and operational stability at screening stage.
Enables diameter back-calculation from volume for early layout.
Accounts for freeboard and operational headspace.
Accounts for access ways, pipe racks, electrical rooms, laydown, and maintainability clearance.
