The following blog about potable reuse was written by student attorney Courtney Cole.
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To learn more about water recycling, I recently toured facilities in both San Diego and Orange County that treat wastewater to better-than-tap quality. I’ll have to admit, I had my reservations. What about all of the teeny tiny bacteria and viruses and…stuff? But that was before I knew how things worked.
Once biosolids are removed, the water undergoes a three-step process: microfiltration, reverse osmosis, and UV + H2O2. Microfiltration uses hollow fibers, similar to straws, with tiny holes (1/300 the diameter of a human hair) in the sides to remove suspended solids, protozoa, bacteria, and some viruses from the water. Next, during reverse osmosis, water is forced through the molecular structure of plastic membranes, removing dissolved chemicals, viruses, and pharmaceuticals. Water is near distilled quality after this step, but as an additional safeguard it is treated with a combination of high-intensity ultraviolet light and hydrogen peroxide. This destroys the DNA of any organism that might have made it past microfiltration and reverse osmosis. So much for my concern about the teeny tiny stuff.
An important part of the tours for me was the drink test. After hearing about destroyed DNA, my main concern was what the water would taste like. I hesitantly filled my test cup and raised it to my nose. It seemed fine, so I drank. Better than fine, the water tasted wonderful! It was clean and refreshing, and better than any bottled water I have ever had.
Aside from tasting great, recycled water has other benefits for San Diego. Over 80% of our drinking water is imported from the Colorado River or northern California, which uses energy and costs money. To address this, Coastkeeper advocates for potable reuse – a process in which highly-treated wastewater is added to local reservoirs to increase drinking water supply. Utilizing recycled water will help secure a local and reliable source of water for our city. And if I’m still here to write this blog post, maybe toilet to tap isn’t so bad after all.