How Clean Is Recycled Water?

By Pat Ferraro, San Jose Inside, 9/15/14

We know all life depends on water. But it’s the quality of that water that determines what can live/thrive on any particular mixture of H2O molecules and varying bits of other planetary elements, including some compounds humans invent.

In California’s rivers, anadramous fish species spawn in the fresh waters of their birthplace and later swim to the ocean to mature in the highly saline waters of the Pacific Ocean. Today, these same species struggle for their very existence amid our super-engineered water capture and diversion systems.

Water for commerce has varying quality requirements. Farmers can use almost anything wet, upstream of the tidal influence in the Delta.

Silicon Valley innovators finally realized reverse osmosis filters could turn tap water into the best solvent salt-free water. Pure water replaced the use of deadly organic solvents, used well into the 1980′s, which resulted in unbearable grief and cost untold dollars.

For the last 50 years, Santa Clara County has been able to grow and prosper with water from remote watersheds. Fifteen percent comes from the snowmelt of Yosemite National Park’s Hetch Hetchy Valley. The San Francisco Public Utilities Commission pipes it around the periphery of the Delta. Another 40 percent of our water comes out of the southern Delta near Tracy, using pumps built in the 1950s and ’60s by the state and federal governments. Our straws in this common pool, though essential to our survival in the past, are but pipettes compared to the cumulative draw of the San Joaquin Valley and the Metropolitan Water District of Southern California.

The quality of this imported water is of great concern to the Santa Clara Valley Water District and everyone else charged with getting adequate and safe water to your home or business. Over a hundred million dollars per year is spent capitalizing and operating water treatment plants, and transforming this downstream water to legal, potable quality. For this reason, local water officials generally support building new infrastructure to enable us to also get cleaner and less salty water further upstream, closer to Sacramento.

This year, with minimal storage remaining in the major reservoirs upstream of the Delta, our imported water is saltier than usual (300 vs. 200 mg/l). If it doesn’t rain next winter, the Delta becomes the ocean, as the rivers run completely dry and tides move the salty water inland.

It’s this pending catastrophe that has caused our local leaders to finally call for recharging our groundwater basins with water produced at the wastewater treatment plants, where currently 150 million gallons per day is wasted to South San Francisco Bay. Silicon Valley manufacturers have 30 years experience using reverse osmosis to rinse electronic components, and that same technology is at the heart of the recently completed Silicon Valley Advanced Water Purification Center.

There are sure to be loud-talking opponents who want to keep this sensible management from happening. But recycled water, produced with well-proven technology, can actually be cleaner than Hetch Hetchy snowmelt. It is a drought-proof water supply, and it is a faster and far more reliable solution than building a new dam north of the Delta. Recycled water is cheaper than desalination and it can be pumped upstream to groundwater recharge areas using existing transmission facilities (purple pipes). Santa Clara Mayor Jamie Matthews said we should accomplish this in a two-year period—the time it took to build the 49ers new stadium.

We can do this Silicon Valley. Our future may well depend on it.

Pat Ferraro served as an elected member of the Santa Clara Valley Water District from 1972-1995 and later served as executive director of the Silicon Valley Pollution Prevention Center. He is currently an adjunct professor at San Jose State University and Santa Clara University, lecturing on water law and policy and water resources management.