GrokSurf's San Diego

Local observations on water, environment, technology, law & politics

Water reuse is imperative for a sustainable San Diego

Posted by George J Janczyn on December 14, 2009

July 2009: low water level in Lake Mead near Hoover Dam

Whether you believe global warming contributes to drought or that when the drought is over our problems will go away, the fact is that water scarcity is not a temporary condition in Southern California. For one thing, our access to Colorado River water is decreasing. But California’s take of Colorado River water is not dropping because of drought or politics. Yes, there is growth and development everywhere and western states are taking more water from the Colorado River than ever, but the reason for our reduction is that we have to stop taking more than we are legally entitled to.

For years California withdrew more than its legal allotment of Colorado River water by as much as 800,000 acre feet per year. This was permitted because other states, primarily Arizona and Nevada, were not taking the full amount they are legally entitled to. But as those states increasingly began taking their share, California was forced to begin making adjustments to live within its means and move to comply with its legal allocation of 4.4 million acre feet per year. So, too, San Diego is adjusting to a reduction in water deliveries from the Colorado River that will be permanent, in addition to the latest cutbacks from Northern California. Plus, even when the Colorado River flows at “normal” levels — a rate which is increasingly uncertain — it may not produce enough water to permit everybody to take their full share, especially when you consider that the allotments were based on unrealistically high flow rate projections.

San Diego’s heavy dependence on Colorado River water places it in a very vulnerable position, especially with the prospect of reduced deliveries from northern California. Fortunately, these days a growing number of San Diegans are becoming more aware of our heavy dependence on imported water and the importance of long-term sustainable approaches to meet our demand. My question is: how much will citizens support further recycling to make San Diego more independent in providing for its water requirements?

The San Diego County Water Authority and the San Diego Water Department began working many years ago on ways to reduce our reliance on imported water. They negotiated the purchase of water conserved by Imperial Valley farmers for transfer to San Diego. We’re currently receiving water under the agreement although two new lawsuits challenging the transfer were recently filed [–yes, technically that’s still imported water]. A new desalination plant is in the works in Carlsbad (that’s still being challenged as well). The San Vicente Dam is being raised to increase its capacity. Additional groundwater sources are being studied. Two water reclamation plants were built to treat wastewater for irrigation and industrial use in the northern and southern regions (and the city could probably use a third for the central areas). There is renewed emphasis on water conservation. And now more important than ever, there’s the possibility of highly advanced treatment of wastewater for indirect potable reuse.

North City Water Reclamation Plant

Actually, the San Diego City Council in 1989 passed an ordinance requiring wide use of recycled water. For whatever reasons, recycling then languished for years. Then growing support for recycling led to the construction of the two recycling plants, but an indirect potable water reuse project was vetoed by Mayor Sanders in 2007. Although scientific studies established that water quality from highly advanced treatment not only equals but exceeds the quality of water that is currently distributed for potable purposes, the mayor and other opponents of the plan used the “toilet-to-tap” label and other inflammatory rhetoric to fight the project. Fortunately, clearer minds prevailed and the veto was overridden by the city council (Mike Lee recounts this history at http://legacy.signonsandiego.com/uniontrib/20080308/news_1n8pipes.html).

The Water Purification Demonstration Project is making some progress now. The project aims to demonstrate the feasibility of providing highly advanced treatment and disinfection for 1 million gallons of water per day, bringing it to indirect potable standards and supplementing the city’s water supplies by blending it with water in the San Vicente reservoir.

The San Diego Water Department is planning to give a presentation on this topic at UCSD sometime in January. They also will submit a public outreach and education contract proposal to the city council in early 2010. Keep your eyes open for announcements. [update below]

A moderate amount of recycled water is being used now, but there’s plenty of unused production capacity. Purifying it to indirect potable standards could and should be a significant component of San Diego’s efforts to reduce reliance on imported water. If the IPR study is successful and the technology is approved for production, the process could produce up to 16MGD of potable water. It absolutely makes sense to reuse as much water as possible that otherwise goes wasted into the ocean. When the Water Department’s outreach and education efforts begin rolling out next year, I hope enlightened San Diegans will reject the fearmongering by opponents and throw their support behind this worthwhile project.

UPDATE Jan 27, 2010:The public outreach contract mentioned above was brought to the Jan. 26 San Diego City Council meeting where they approved “an Agreement between the City of San Diego and RMC Water and Environment, to perform the Project Management and Public Outreach for the Demonstration Project, in an amount not to exceed $3,281,353.” (City Council Docket Item #334)

For continuing coverage on indirect potable reuse, please see the Indirect potable reuse page


“In an effort to develop local sustainable water supplies, the City of San Diego evaluated indirect potable reuse. A series of pilot scale tests were conducted using tertiary water from an existing water reclamation plant. The pilot train consisted of ultrafiltration (UF), reverse osmosis (RO) and advanced oxidation using ultraviolet light and peroxide. Program objectives included: water quality performance of the treatment train; comparison of product water quality to existing potable source water quality; impact of advanced oxidation on endocrine disrupting compounds (EDC), pharmaceuticals and personal care products (PPCP); and evaluate RO integrity monitoring methods. Results showed: effective removal of contaminates by the treatment train; a product water with a mostly lower concentration of contaminates than existing source water supply; advanced oxidation removing >99% of most EDC/PPCPs; and a high correlation between integrity testing methods.” / Proceedings of the Water Environment Federation 2007

“A diversified portfolio of water sources is required to ensure public health, as well as social, economical and environmental sustainability. One of the options considered is the augmentation of drinking water supplies with advanced treated recycled water. This paper aims to provide a state of the art review of water recycling for drinking purposes” / Int J Environ Res Public Health. 2009 March

“Today, cities around the world are shifting away from the historical focus of wastewater management (i.e. the miracle of making the wastewater go away somewhere where we can’t see it) and adopting a new paradigm of re-use.” / Boing Boing

“On November 18, 2009 the Building Standards Commission unanimously voted to approve the California Dual Plumbing Code that establishes statewide standards for installing both potable and recycled water plumbing systems in commercial, retail, and office buildings, theaters, auditoriums, condominiums, schools, hotels, apartments, barracks, dormitories, jails, prisons, and reformatories. The code is set to be published in July of 2010. The new code will be effective January 2011.” / California Department of Water Resources

Chart comparing San Diego’s current water quality vs. other water agencies that employ indirect potable reuse shows very competitive quality with reuse / San Diego County Taxpayers Association

Summary of costs and benefits of water supply alternatives / California Coastkeeper Alliance

Pharmaceuticals a problem for NF wastewater reuse / Desalination and Water Reuse


Additional references (these have been incorporated into a selected bibliography maintained on the Indirect Potable Reuse page)

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