Spain faces changing water use as drought persists and desalination grows
The current drought, only partially eased by recent rains, is reshaping how water is consumed in Spain. Desalination plants are being called upon to take on a larger share of supply as authorities consider building more facilities and expanding existing ones. Yet the economic and ecological costs of these plants remain high, and desalination is not simply a matter of turning seawater into drinkable water.
For example, Barcelona hosts Europe’s largest desalination plant. In 2009, boats equipped to carry water were deployed after a severe drought, ensuring a steady supply for residents. Since then, production from this facility has varied, but it has become an indispensable part of the city’s water strategy as conditions evolve.
Two years before the current drought, rivers provided 63% of Barcelona’s drinking water, while wells tapped 34% from underground aquifers, and desalination accounted for only 3%, according to data provided to the AP by the city’s municipal water company. Today, desalination represents about 33% of Barcelona’s drinking water, wells supply roughly 23%, and river flows have declined to about 19%.
Hypersaline waste from desalination plants
Desalination helps alleviate drinking water shortages but comes with side effects, especially due to high energy needs and the discharge of highly saline brine back into the sea.
Discharging brine from desalination into marine environments raises concerns among scientists and conservationists. Brine, the saline rejection concentrate, can affect marine ecosystems, including sensitive Posidonia meadows that support diverse life underwater. Brine is more than a simple salt solution; it can carry residual chemicals from the desalination process.
The scale of brine discharge is notable. On average, for every 0.45 liters of fresh water produced, about 0.55 liters of brine is generated as waste.
Since Lanzarote installed Europe’s first seawater desalination plant in 1964, Spain has become a major player with one of the world’s largest desalination capacities. Some 800 water treatment plants spread across the country supply drinking water, agriculture, and industry.
Energy consumed by a desalination plant
The Center for Ecological Research and Forestry Practices (CREAF) at the Autonomous University of Barcelona has warned about the energy footprint of desalinated water production.
Photographs and reports show desalination facilities like Lanzarote’s plant, underscoring the energy costs involved. Recent analyses note that desalination consumes substantial energy, though best-performing systems have cut consumption from roughly 8 kWh per cubic meter in the 1970s to around 2.3 kWh/m3 in optimized configurations. Still, average energy use hovers around 4 kWh/m3 today.
Comparative estimates from CREAF researchers suggest that a seawater desalination plant producing at least 1.5 million cubic meters per day can consume as much energy as powering approximately 639,000 homes, highlighting the scale of demand. A typical household is estimated to use about 3,847 kilowatt-hours per year.
There are desalination plants driven by solar energy, but few large-capacity plants rely entirely on this source. In Spain, a new water treatment project often implies a significant uptick in fossil-fuel energy use during startup and operation.
Inside the desalination facilities, energy demand remains a critical consideration as operations expand. Greenpeace and other environmental groups acknowledge that desalination can be necessary to maintain water supplies in certain cases, but they urge careful measures to minimize environmental impact.
One potential path to relief involves restoring riverbeds obstructed by dams and other barriers, which would improve natural water flow and reduce reliance on desalination. Redirecting irrigated crops and reducing nitrate leakage from livestock and agricultural runoff into underground aquifers could also help increase available water volumes.
Further discussion on these strategies continues as policymakers weigh the trade-offs between securing water supply and protecting ecosystems.
Environmental department contact information and details about official programs have been removed to maintain privacy and focus on the topic.