Desalinated water is toxic solution to crisis

by Leonardo Castaneda

 Rob Piper, Staff Artist
Rob Piper, Staff Artist

Few things are as vital as water to our survival, not just individually but as a nation. The struggle to secure this precious resource will only become more desperate in the coming years.

Recently, KPBS reported four key water districts in the Southwest, including the San Diego County Water Authority, are turning to seawater in an attempt to manufacture water security. But plans to build desalination plants in Southern California have stalled recently because of legal and environmental challenges. Undeterred, they are now hoping to build a plant just 15 miles south of the border in Rosarito, Mexico.

There are currently two competing proposals, both centered around an existing power plant in Rosarito. One proposal would produce 50 million gallons of water a day, which the U.S. and Mexico would then split. That plant has the best chance of being built and has recently passed an early round of design tests. The second, more ambitious idea is to build a plant that could produce as much as 100 million gallons of water a day. The plant would be financed by the Cayman Islands-based Consolidated Water Co. alongside Mexican investors, and would send much of its output to the U.S.

Regardless of which plant gets built, desalination in Mexico is far from the solution to the region’s water woes. It simply kicks the can of water security a few years down the road in a cost-ineffective and environmentally destructive manner.

The process of turning seawater into tap water is a seemingly simple yet destructive one that relies on reverse osmosis. In case you’ve forgotten high school biology, here’s how it works: First, huge amounts of ocean water are sucked into the plant. Often fish eggs, larvae, plankton and other organisms vital to the ocean’s ecology are sucked in with the water. The water then goes through a series of membranes that filter the water until it’s safe to drink. Alongside the safe drinking water, brine is created. Brine is a mixture of extremely salty water, the carcasses of all the dead organisms captured and killed by the process and all the toxic chemicals used to purify the water. This brine is pumped back into the ocean, where it can raise the toxicity and salinity of the area near the plant and destroy the fragile coast ecosystem.

And in the end there is no guarantee the water destined for human consumption is truly safe. Toxic chemicals such as boron, present in seawater and other chemicals and organisms that leak in during the desalination process, can bypass filters unless expensive purifying steps are taken.

One of the main reasons water districts and investors want to desalinate water in Mexico is to circumvent the environmental and legal regulations in California. To assume these same people will go through great lengths and costs to ensure the quality of that water is a foolish gamble we cannot take.

But even beside the environmental damage and health risk, desalination isn’t an economically viable source of water for San Diego. One of the most cost-effective plants in the world, being built in Carlsbad, can sell water for just $2.90 per kilogram of water. That’s inexpensive compared to other plants around the world that average as much as $9-$10 per kilogram. But it’s still more than the current cost of water. For areas such as the Otay Water District, that means a 45 percent rate increase. And the cost of desalinated water is only going to get higher.

Because desalination is highly energy intensive, energy costs account for almost half the cost of producing desalinated water. As fuel prices continue their steady rise into the stratosphere and energy becomes more expensive, desalinating water will only become more expensive. The treatment plants add to the problem by increasing demand, leading to higher energy prices.

Added to the already high cost of desalinated water is the small problem of getting it here from Mexico. One way would be to let Mexico keep the water from the plant and reduce its allotment from the Colorado River. However, Mexican officials refuse to reduce its already shrinking share of the river’s water. The only alternative is to build a pipe across the border to transport the water. That would require a presidential permit from the State Department, and could potentially make the plant’s water prohibitively expensive.

The truth is desalination plants offer temporary water security at huge economic and environmental costs. There is a simpler path toward better long-term water security for the region. Instead of making more water, we should increase water conservation and efficiency. By increasing the cost of water in the region, we can help reduce demand to a sustainable amount.

We have to accept that expensive water is our new reality. The difference is what we will be paying for. We can pay more to damage the environment and increase our reliance on carbon and fossil fuels. Or we can pay more to use our resources in an intelligent and sustainable way.