Desalination typically costs between $0.40 and $2.00 per cubic meter of freshwater produced, depending on the source water, plant size, energy prices, and local regulations. That translates to roughly $500 to $2,500 per acre-foot, though some facilities run higher. For context, a cubic meter is about 264 gallons, enough to supply one person for several days in a typical household.
The wide range exists because desalination isn’t one process with one price tag. A massive plant treating seawater on the coast of Saudi Arabia operates in a completely different cost universe than a smaller facility in Southern California dealing with stricter environmental rules and expensive electricity. Understanding where the money goes helps explain why prices vary so much.
Where the Money Goes: Capital vs. Operating Costs
The total cost of desalinated water splits roughly 40% capital expenses and 60% operating expenses. Capital costs cover the plant itself: membranes, pumps, intake structures, pipelines, and permitting. Operating costs include energy, chemicals, labor, membrane replacement, maintenance, and disposing of the concentrated brine left over after treatment.
Energy dominates the operating budget. Electricity alone accounts for about 46% of all operating costs, making it the single largest variable in what you ultimately pay for desalinated water. A modern seawater reverse osmosis plant consumes between 3.5 and 4.5 kilowatt-hours for every cubic meter of freshwater it produces. That figure includes the pretreatment and post-treatment steps, not just the membranes themselves. The theoretical minimum energy needed is only about 1 kWh per cubic meter, so real-world plants use roughly three to four times the physical limit, leaving room for future efficiency gains.
Membrane replacement is another recurring expense. Reverse osmosis membranes degrade over time and typically need replacing every two to five years. How quickly they wear out depends heavily on the quality of the incoming water and how well the plant pretreats it before pushing it through the membranes. Regular chemical cleaning extends membrane life and reduces replacement costs, but it’s an ongoing maintenance commitment either way.
Seawater vs. Brackish Water
The saltier the water, the more energy it takes to push freshwater molecules through a membrane. Seawater contains around 35,000 milligrams per liter of dissolved solids, while brackish water (found in underground aquifers and some estuaries) typically contains 1,000 to 10,000 milligrams per liter. That difference makes brackish water desalination significantly cheaper per cubic meter.
There’s a partial offset, though. Brackish water usually comes from wells, and pumping it to the surface requires more energy than drawing seawater from an open ocean intake. Still, the overall energy balance favors brackish sources, which is why inland brackish desalination plants tend to produce water at the lower end of the cost range while large seawater facilities cluster toward the middle or upper end.
The Global Price Floor
The cheapest desalinated water in the world comes from large-scale plants in the Middle East, where economies of scale, low energy costs, and streamlined permitting drive prices down. A facility in Saudi Arabia operated by ACWA Power set a record-breaking tariff of $0.41 per cubic meter, delivering clean water to more than 3 million people. That project combined desalination with solar power, cutting energy costs further.
These rock-bottom prices aren’t easily replicated elsewhere. They depend on government-backed financing, enormous plant capacity, abundant sunshine for solar integration, and relatively lenient environmental discharge rules. But they do establish a floor that shows how cheap desalination can get under ideal conditions.
What It Costs in the United States
American desalination is considerably more expensive. The Carlsbad Desalination Plant near San Diego, the largest seawater desalination facility in the Western Hemisphere, produces water at about $3,500 per acre-foot. That makes it the region’s most expensive water source and a frequent target of critics concerned about rising water bills.
Several factors push U.S. costs higher. Electricity prices in California are well above the global average. Environmental permitting adds years to project timelines and requires expensive mitigation measures. Labor costs are higher. And the plant’s financing structure, which includes payments to a private operator, builds in profit margins that government-run facilities in the Gulf states don’t carry. San Diego water customers have even owed the plant operator tens of millions of dollars for water the utility contracted to buy but didn’t need, illustrating how long-term purchase agreements can inflate the effective cost.
The Cost of Brine Disposal
Every liter of freshwater produced leaves behind a concentrated stream of salt and minerals called brine. Disposing of this byproduct adds cost, though perhaps less than most people assume. Data from desalination plants in Spain found that diluting brine before discharging it to protect coastal ecosystems added roughly 1.7% to total energy costs on average. In practical terms, that worked out to less than one euro cent per cubic meter of water produced.
The cost fluctuates with how much dilution regulators require. At a 4:1 dilution ratio, brine management added about 3% to energy costs. When production dropped and plants had to dilute at ratios above 7:1, that figure climbed closer to 4%. In regions with stricter marine protections or where brine must be piped inland to evaporation ponds, costs can be substantially higher. Some U.S. projects have seen brine management add 5% to 15% to total project costs, depending on local geography and regulations.
What Drives Prices Down
Desalination has been getting steadily cheaper. Modern reverse osmosis systems use far less energy than earlier generations, thanks to better membranes and energy recovery devices that capture the pressure from outgoing brine and redirect it to incoming seawater. These improvements have cut energy consumption by more than half compared to plants built in the 1990s.
Plant size matters enormously. Larger facilities spread their capital costs across more water, which is why the biggest plants in the Gulf states and Israel produce water so much more cheaply than smaller municipal systems. A plant producing 30,000 cubic meters per day operates in a fundamentally different cost bracket than one producing 5,000.
Renewable energy integration is the next major cost lever. Solar-powered desalination eliminates the exposure to volatile electricity prices that makes operating budgets unpredictable. As solar panel costs continue to fall and battery storage improves, pairing desalination with dedicated renewable energy is becoming economically competitive in sunny regions. The combination of more efficient membranes, better energy recovery, and cheaper renewables is pushing desalination costs downward at a pace that makes it increasingly viable for water-stressed cities worldwide.
How It Compares to Other Water Sources
Desalinated seawater remains more expensive than most conventional freshwater sources. Treated surface water from rivers and reservoirs typically costs $200 to $700 per acre-foot in the U.S., and groundwater pumping is often cheaper still. Recycled wastewater, which is gaining traction in drought-prone areas, generally falls between conventional supply and desalination in price.
The comparison shifts, though, when conventional sources become unreliable. During severe droughts, the cost of imported water spikes, water rights become more expensive, and restrictions on use carry their own economic toll. Desalination’s price is high but predictable. It doesn’t depend on rainfall, snowpack, or political negotiations over river allocations. For coastal cities facing growing water scarcity, the relevant question isn’t whether desalination is cheap in absolute terms, but whether it’s cheaper than the alternative of not having enough water.