Cost Estimation

Desalination Equipment Cost Estimation: Skid Quotes and Cost per Cubic Meter

Where the money actually goes in membrane water treatment: materials, labor, energy, consumables, and brine, and how to build a quote that survives an audit.

Desalination cost questions come in two flavors: what a membrane skid should sell for, and what a cubic meter of water costs to produce. Both get misquoted for the same reason, estimators price the visible hardware and skip the recurring consumables. Delivered water from a brackish RO plant typically runs $0.30 to $0.60 per m3 all in, seawater $0.60 to $1.20 per m3, and equipment capex lands between $800 and $2,500 per m3 per day of installed capacity depending on salinity and site. This guide breaks both stacks down line by line and shows where quotes go wrong.

On the equipment side, materials carry 55 to 65 percent of a typical skid price. Standard 8 inch brackish elements run $450 to $700 each and seawater elements $600 to $900, so a 29 vessel, 203 element train holds $90,000 to $180,000 in membranes alone. Add FRP pressure vessels at $1,500 to $3,000 each, a high pressure pump and VFD that together absorb 25 to 35 percent of material cost, plus super duplex piping on seawater duty at 3 to 4 times the price of 316L. Lock membrane pricing with a quote under 60 days old; element prices have moved 10 to 20 percent in a single year.

Assembly labor is the second stack. A mid size skid consumes 250 to 600 shop hours across frame fabrication, piping, instrument wiring, and element loading, and loading alone runs 15 to 25 minutes per element with two techs. The Membrane Skid Assembly Labor calculator converts your element count, vessel count, and instrument count into hours so you quote from a model instead of a guess. Burden the hours at a full shop rate, typically $65 to $95 per hour including fringe and supervision, not the bare wage. Factory acceptance testing costs real money too; the Pressure Vessel Test Energy Load calculator prices the electricity for hydrotest and performance runs, often 500 to 2,000 kWh per skid.

Build the quote bottom up: materials at quoted prices plus 3 to 5 percent freight, labor hours times burdened rate, overhead applied at 15 to 25 percent of prime cost, then margin of 10 to 20 percent depending on competition. Add explicit lines for engineering at 8 to 12 percent of sell price, commissioning travel, and a 5 percent contingency on any scope with unproven feed water. The classic failure is quoting scrap and rework at zero; element handling damage alone typically eats 0.5 to 1 percent of membrane value, and a single dropped 8 inch seawater element is $700 gone.

On the operating side, electricity is 30 to 50 percent of production cost, so start there. The Pump Energy Cost calculator turns motor kW, run hours, and tariff into an annual figure you can divide by production. Chemicals come next: antiscalant at a 2 to 4 ppm dose costs $0.01 to $0.03 per m3, plus coagulant, biocide, and dechlorination. The Pretreatment Chemical Cost calculator totals dose rate times flow times unit price across each chemical. Cartridge filters look trivial at $5 to $15 per element, but a 40 cartridge housing changed every 4 weeks is $3,000 to $9,000 per year plus labor, which the Cartridge Replacement Workload calculator quantifies.

Membrane replacement is the sneakiest line because it is lumpy. Amortize it: replacing 12 percent of a 203 element inventory each year at $600 per element is about $14,600 annually, or $0.012 per m3 at 1.2 million m3 per year of production. Cleaning behaves the same way: a CIP event consumes chemicals, heated water, operator hours, and 8 to 24 hours of lost production, typically $2,000 to $6,000 all in, and the CIP Cleaning Cycle Cost calculator itemizes it. Do not forget the water you never made; the Membrane Fouling Loss calculator prices the production a fouled train fails to deliver between cleanings, often a larger number than the cleaning itself.

Brine disposal can quietly dominate inland projects. Ocean outfall costs cents per m3, but sewer discharge surcharges run $0.30 to $1.50 per m3 of concentrate, deep well injection $0.10 to $0.60, and trucking $8 to $25 per m3 hauled. At 75 percent recovery every 3 m3 of product creates 1 m3 of concentrate, so a $0.50 per m3 disposal fee adds $0.17 to every m3 of water sold. Run the Brine Disposal Cost calculator during the proposal stage, not after award; more inland RO quotes die on brine than on membranes.

Audit any estimate against four failure patterns. One, energy priced at last year's tariff; use the current contract rate plus demand charges. Two, consumables annualized from vendor optimism rather than site history; use 12 months of actual cartridge and CIP records where they exist. Three, labor estimated per skid instead of per element and per instrument, which underquotes large trains by 20 to 30 percent. Four, no escalation on multi year supply agreements; index membranes and chemicals to a published producer price index. An estimate that survives those four checks is defensible in front of any buyer.

Published 2026-07-02.