5 Reasons to Be Wary of Desalination

Desalination is not a cure-all, writes our science and policy chief Rita Kampalath.

It costs too much.  The price of a gallon of water produced by a new desal plant in Carlsbad is expected to cost twice as much as a gallon derived from recycled water, and three times or more than a gallon sourced from groundwater storage, or conservation through programs like turf replacement rebates. For desal plants to make financial sense, cities must agree typically to long-term contracts. Given our boom-and-bust rain cycles in California, we will surely see more deluges in years to come. The fixed costs of desal plants won’t just go away in rainy years when their water isn’t needed.

It uses too much energy. Currently, the most energy-intensive portion of our water supply is the water that we import from Northern California through the State Water Project and the Colorado River. That water has to travel over 600 miles to get to us, yet it still uses less energy per gallon (though not by much) than desalinating ocean water. Desalination simply can’t compare to relatively low-energy water supplies like groundwater or stormwater capture (or just using less water, which takes no energy at all!) More energy means higher costs, but it also means more greenhouse gases.

It kills marine life. Ocean intakes can suck up millions of gallons of seawater daily, along with any marine life unlucky enough to be in close proximity. Subsurface intakes extract water underneath the seabed or nearby beach and have less negative impacts to animals. But both methods leave an enormous by-product of salty brine, a toxic by-product that is challenging to dispose of.  Unfortunately, many facilities want to use surface intakes because they can be cheaper and tend to have a greater capacity. California’s recently adopted desalination policy mandates that facilities use subsurface intakes when possible, but we’re wary that the desal industry will find loopholes.

It takes too long. From start to finish, getting a desalination plant up and running is at least a multi-year process. Construction on the Carlsbad plant started in 2012, and isn’t expected to be completed until later this year – and that doesn’t take into account all the planning and design that had to happen as well. This drought is happening now, and it’s just a simple fact that desalination can’t start quickly enough to help. And as crazy as it seems right now, in a year or two, we may be out of the drought, especially with forecasters predicting El Nino conditions. We don’t want to commit ourselves to spending over a billion dollars on something that we may not even need by the time it’s completed.

It eclipses better options.  The Carlsbad plant, which is the largest plant in the Western hemisphere, can only produce about 7% of San Diego’s water supply! How about we use that billion dollars to cut down our water usage by that percentage instead? Let’s invest in proven processes that are more efficient, take less money and have much less negative impacts on the environment. Instead of building desal plants, we should be investing in facilities that capture and reuse of urban runoff, as well as fast-tracking the recycling of highly treated wastewater from Hyperion and other plants.