Efforts to curb the consumption of water are getting great results and making expensive desalination plants obsolete.

Last month, the regional water agency that serves the city of San Diego approved a plan to buy seawater made drinkable through a process called desalination. If built, the plant that will provide that water, known as the Carlsbad Desalination Project, will be the largest of its kind in the Western Hemisphere.

While heralded by some as a panacea to our planet’s water problems, desalination plants such as Carlsbad have proven to be, at best, a small-scale solution when water resources are very limited. At worst, the technology is being pushed by private interests looking to profit from the sale of water while sticking the public with its high financial and environmental costs. In most places, desalination is unnecessary, especially since we’re already making great progress in making water available simply by using less of it.

That plant would cost $500 million to build and would process 50 million gallons of water per day. It would be privately owned and controlled, and has been in the works for over 15 years. The process has been riddled with cost uncertainties and Poseidon continues to lobby public agencies for subsidies.In the United States, there have been dozens of proposed desalination facilities, mostly in California and Florida. Yet few have actually been built, and there remains only one major facility, which is in Tampa Bay Florida. Poseidon Resources, a privately owned corporation, won the initial contract to build the Tampa plant, but was never able to get it to work as the project was years late and costs tens of millions of dollars more than projected. Poseidon was ultimately bought out by the city of Tampa. Poseidon is the same company behind the Carlsbad plant that was just approved for San Diego.

Yet there is no real need for the project. Here are three reasons why Californians should look to other sources for their water.

First, there’s the good news is that efforts to decrease water consumption are finally making good. Water usage across southern California has dropped 10 to 15 percent in the last few years, and there is much more room for improvement, as about half of residential water use is for outdoor irrigation. Agriculture uses about 80 percent of the water in California, according to the Pacific Institute, so further cuts can be focused there. Increased water efficiency and waste prevention are the cheapest and greenest ways to make more our water supply more reliable.

Second, desalination is an energy hog, making it the most expensive source of potable water. Pushing ocean water through a filter at high velocity requires tons of energy, and thus, tons of money. Desalinated water typically costs over $3,000 per acre foot of water, whereas simple efficiency measures cost between $300 to $800 per acre foot. A now-defunct proposed desalination plant in Marin County, Calif., would have doubled the energy usage of the area’s water district, already the single largest user of energy in the county. In a time when the climate crisis demands that we make our society as energy-efficient as possible, desalination would take us in the opposite direction.

We won’t need the expensive and dirty technology of ocean water desalination, if we take these opportunities to make more of the water we have.Our nation has serious water problems, and the choices we make now will affect our environment and our budgets for decades to come. Our existing water infrastructure is leakingand in serious need of being rebuilt and upgraded. As a nation, we fail to effectively capture and use stormwater and rainwater, which are often polluted running off urban landscapes and into waterways. Finally, over 70 percent of our nation’s water is expended on agriculture, a sector that could stand to be much more efficient.