San Diego imports 85% of its water supply from the Colorado River and Northern California Bay Delta. Over the past 15 years, the cost of importing the water has tripled with the current cost of imported water ($1,200 to $1,400) expected to double in the next 10 years. In addition, the city will become more vulnerable to droughts, climate change and natural disasters as the century progresses.
To lower operational costs and become more resilient, the City of San Diego is embarking on the phased, multi-year Pure Water San Diego Program that will see recycled water provide 1/3 of the city’s water supply locally by 2035 and reduce the city’s ocean wastewater discharges by more than 50%.
Pure Water, Pure Gold for San Diego
Instead of wastewater being treated at Point Loma and discharged into the ocean, the Pure Water Program will direct wastewater flows away from Point Loma and use proven water purification technology to produce safe, high-quality purified drinking water. Specifically:
- Wastewater is treated to recycled water standards at an existing water reclamation plant
- Recycled water is treated at a Pure Water Facility, resulting in purified water
- Purified water is sent to an existing reservoir and blended with imported and local water supplies
- Water is treated further at an existing drinking water treatment plant
- Potable water is distributed to customers via the city’s existing water supply system
Protecting public health
The new North City Pure Water Facility will be built nearby an existing water reclamation plant and will use a proven 5-step water purification process of:
- Biological Activated Carbon
- Reverse Osmosis
- UV/Advanced Oxidation
To further protect public health, the purified water has a detention time in an environmental buffer (groundwater basin or surface water reservoir) prior to being blended into the drinking water system. Because San Diego does not have viable groundwater basins the purified water will be sent to Miramar Reservoir with the pumping of the water to the reservoir powered by renewable energy. In total, 30 million gallons of purified water will be piped to Miramar Reservoir per day.
Recreational opportunities at Miramar Reservoir
Miramar Reservoir itself offers residents multiple recreation opportunities with a 5-mile-long paved service road encircling the reservoir offering cycling, jogging, walking, picnicking and other outdoor activities. In addition, there are 18 BBQs and 48 picnic tables for visitors to utilize. Even fishing is permitted on the reservoir for those with a city fishing permit.
Cities need to consider alternative water supplies to reduce operational costs and enhance resilience to climatic extremes.
*Robert C. Brears is the author of Urban Water Security (Wiley), and of the forthcoming titles Blue and Green Cities (Palgrave Macmillan) and The Green Economy and the Water-Energy-Food Nexus (Palgrave Macmillan). He is Founder of Mitidaption, which consults on climate change risks to business, governance and society.