This East Bay Farm Uses Recycled Water to Grow Food for Kids

When most people see a plot of land sandwiched between the runway exclusion zone of a municipal airport and a wastewater treatment plant, they see only industrial blight. But when activist Carolyn Phinney laid eyes on such a plot, she saw nothing but possibility.

Over the last decade, Phinney and a band of farmers, sustainable food enthusiasts, and other people unafraid to get their hands dirty have volunteered their time to transform a 15-acre chunk of land in Martinez, California into the Coco San Sustainable Farm. The urban farm uses recycled water from the nearby treatment plan to grow fresh, sustainable produce for local schools. Lots of produce — over 100,000 pounds per year as of 2023.

(I originally learned about the farm because I’m somewhat obsessed with my local wastewater utility, the Central Contra Costa Sanitary District.)

Central San publishes a twice-yearly newsletter called Pipeline, which the state requires it to deliver to every resident it serves. By all rights, this publication should be terrible — “state-mandated wastewater treatment newsletter” doesn’t exactly scream editorial quality.

But Pipeline rocks. It’s full of original photography, its articles are well-written and often witty, and it even includes things like waste-themed crossword puzzles and games for kids. Even its name is mildly self-referential and amusing. The newsletter’s quality is reflective of the overall organization — Central San is considered one of the best utilities in the country, and consistently wins the industry’s top honors.

In 2019, I reached out to Central San board member Mike McGill to volunteer my services as a professional photographer. He suggested I check out the amazing work Phinney and her crew do with the utility’s recycled water. And so one morning in January of 2019, I connected with Phinney and found myself wandering between rows of fast-growing plants at CoCo San Sustainable Farm.

The farm occupies a strange space. Situated just outside the Buchanan Field Airport — and flanked by a concrete supplier and a paint store — it feels patently industrial.

Yet at the same time, the spot has plenty of natural beauty. Mount Diablo looms in the background, and a creek runs just alongside the farm. If you squint really hard and ignore the construction equipment parked just beyond, you might think that you’re in some untouched, pastoral part of the Central Valley.

Photo: Courtesy of the author

When Phinney and her team first started CoCo San Sustainable Farm, the soil was terrible. The first order of business was to improve it as much as possible. Local businesses donated materials and equipment, and the farm’s volunteers spread new soil and carefully tended it.

Phinney told me that the farm encourages the growth of mushrooms, bacteria, and fungi in order to improve the soil naturally.

Holding up a handful of loamy earth, Phinney showed me the tiny white tendrils of mushroom mycelium, which transport nutrients through the soil and help to feed the farm’s plants.

The farm also encourages the presence of beneficial insects like ladybugs, which help to control pests without the use of chemicals.

All these measures improve the farm’s sustainability. But the farm’s most innovative elements is where it gets its water. In drought-ridden California, water is a precious resource. For years, utilities like Central San have recycled their wastewater, treating it aggressively before pumping it through special purple pipes to nearby customers.

Photo: Courtesy of the author

Most of the time, recycled water in the Bay Area is used for tasks like filling municipal fountains or irrigating highway median strips. But as CoCo San Sustainable Farm shows, the water can be used for so much more — it can be a vital resource for growing healthy, local food on urban farms.

In partnership with Central San, the farm receives recycled water from the adjacent treatment plant.

The water travels through a special pipeline to reach the farm. The distinctive purple pipes which carry it ensure that the water isn’t confused for conventional drinking water accidentally. The farm’s water is considered agricultural-grade, which means it’s safe to use on plants but not to drink directly.

When the water reaches the farm, it’s piped through a special drip irrigation system, which delivers it directly to the roots of the growing plants.

In California as a whole, recycled water is often used for agricultural irrigation on massive factory farms. It’s also for tasks like cooling industrial equipment.

But using it for small-scale urban agriculture is much rarer. CoCo San Sustainable farm hopes to change that, demonstrating how this sustainable resource can be put to productive use locally, potentially addressing issues with food deserts and a lack of healthy produce in public schools.

How well does it work? According to Phinney, the proof is in the produce. Phinney told Salon that the farm’s vegetables “look like they’re on steroids”, and that her zucchini plants are 8 feet across, whereas most are around 30 inches. This is likely due to the care put in by Phinney and other volunteers, but also to the high nutrient content of the recycled water — a kind of natural fertilizer.

During my visit, Phinney plucked colorful radishes from the farm’s soil. Beans, broccoli, and other vegetables grew nearby.

The farm also grows potatoes, squash, tomatoes, and more. Produce grown on the farm goes to local schools, where it provides much-needed greenery in the school lunches of Bay Area students.

Photo: Courtesy of the author

CoCo San Sustainable farm feels like an agricultural oasis in the midst of a region of the Bay Area which is otherwise often heavily industrial, or densely residential. Going there feels like stepping outside the bounds of daily Bay Area life, even if just for a couple of hours.

While I was there, another volunteer dropped by to help tend the plants. He talked with Phinney about “draining the swamp.” At first, I thought he was making a political reference. But I eventually realized there was an actual swamp on the property, and they were literally talking about the best ways to drain it. In a region that is often incredibly fast-paced and sometimes culturally divided, it’s nice to step aside for a moment and connect with the earth.

Many people seem to feel the same, as the farm has a strong volunteer base (Phinney herself is a volunteer). Much has changed since my visit, too. A new donation allowed the farm to build a large solar greenhouse, which will expand its operations.

Still, CoCo San Sustainable Farm is operating at only a fraction of its capacity, and there’s still plenty of room to grow. Phinney told me that the farm encompasses 15 acres, but less than half an acre is currently planted. Fully scaled up, the farm would generate 500,000-plus pounds of produce for local schools, and put many thousands of additional gallons of wastewater to good use.

Want to help out?

CoCo San Sustainable farm always needs volunteers, especially around busy harvest times. Email if you’d like to visit the farm or offer your services/manual labor. You can also donate to support the farm’s operations. CoCo San Sustainable farm is affiliated with AgLantis, a 501c-3 nonprofit, making donations potentially tax-deductible.

You, too, can also visit to learn more about sustainable urban farming, water conservation, and how to make a donation to the nonprofit.

Oh, and those radishes are pretty impressive, too.

Thomas Smith

Thomas Smith is a food and travel photographer and writer based in the San Francisco Bay Area. His photographic work routinely appears in publications including Food and Wine, Conde Nast Traveler, and the New York Times and his writing appears in IEEE Spectrum, SFGate, the Bold Italic and more. Smith holds a degree in Cognitive Science (Neuroscience) and Anthropology from the Johns Hopkins University.

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