Desalination

Reads at about grade 6Both sides shown8 sources cited

Desalination is a way to make drinking water by taking the salt out of ocean water.

What it is

Desalination turns salty ocean water into fresh drinking water. Most plants use a method called "reverse osmosis," pushing seawater through fine filters, called membranes, that trap the salt. California's biggest desalination plant sits in Carlsbad, near San Diego. Its main strength is reliability: the ocean never runs dry, so the supply holds up even in a long drought. But desalination carries three real costs. The first is money -- water from the Carlsbad plant costs about $1,300 to $1,400 per acre-foot (an acre-foot is roughly a year of water for two or three homes), which is on the high end for California water right now. The second is energy: running the plant takes a lot of electricity. The third is harm to sea life -- the intake pipes suck in and kill fish, eggs, and tiny plankton, and the leftover water, very salty "brine," gets dumped back into the ocean. California law now makes plants use the best available technology to limit this harm. Experts mostly agree on these facts. They disagree on one question: is desalination's steady, drought-proof supply worth its higher price? Some say build now; others say lean first on cheaper choices, like using less water and reusing it. So far, California has approved very few new plants.

How it works

California often faces droughts. Its cities lean on water piped in from far away, much of it from the Colorado River and from Northern California's rivers and snowpack -- and in dry years, those sources shrink. Desalination offers another path: the Pacific Ocean is always there. San Diego bet on the idea and built the Carlsbad plant, which is still running today. But desalination is hard -- it costs a lot to build, it takes a lot of energy to run, and environmental groups worry about ocean life. In 2022, California regulators rejected a second big plant, planned for Huntington Beach, saying it cost too much and would harm the sea. That fight came to stand for the whole debate. Supporters see desalination as insurance against a drier future. Critics say California should first do the cheaper, greener things -- use less, reuse more, catch rainwater -- before spending big on the ocean.

The debate — equal weight, both sides

The case for building ocean desalination

Cross-cutting — not left vs. right. Made most often by coastal water agencies, business and pro-growth groups, and some free-market conservatives who stress reliable supply and cutting permit red tape.

California's water future is shaky. Cities like San Diego sit at the end of long pipelines, depending on the over-used Colorado River and a shrinking Sierra snowpack -- and in a drought, those supplies drop. But the ocean does not. That is the heart of this case: a local supply the region controls, one that does not fail in a dry year. Supporters call the Pacific Ocean "the ultimate drought-proof resource." The Carlsbad plant has run for years, and its water is "reliable regardless of drought, shrinking snowpack, below-average rainfall." Real water safety, they argue, needs many sources, not just one. Supporters agree that saving and reusing water helps, but you cannot save water you do not have -- when the next big drought hits, a plant that runs rain or shine earns its price. They also say the real barrier is not cost but red tape: lawsuits and slow permits push the price up. And the energy cost, they argue, is small -- "by increasing our electricity demand by barely more than one percent, we could add a million acre feet to our urban water supply." Cut the red tape, they say, and desalination pays off.

The case for cheaper, greener options first

Cross-cutting. Made most often by environmental groups, many water economists, and ratepayer advocates focused on cost and ocean harm; spans the left and some fiscal conservatives wary of the price.

Desalination is the most costly and most harmful way to get water, so California should use it last, not first. Take price first: the Pacific Institute says this water "can cost upwards of $1,900 per acre foot," far more than the cheaper options -- saving water, catching stormwater, and reusing used water -- which critics say should come first. Desalination also harms the sea. Its intake pipes pull in and kill fish, eggs, and larvae, and the leftover salty water, called brine, is dumped back offshore. This harm helped stop the Huntington Beach plant in 2022; one estimate said it would "kill marine life in about 275 million gallons of seawater per day." A local water watchdog group agreed, finding "more cost-effective and less environmentally damaging water supply projects" for the region. Critics do not rule out the ocean for good. First, they say, use less and reuse more, and catch more stormwater. Then, only if a real gap is left, turn to desalination.

Sources

Behind the summary

Cited by "The case for building ocean desalination"

Cited by "The case for cheaper, greener options first"

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