Earth’s water has always been recycled. We drink the same water as the dinosaurs. The natural water cycle evaporates water from the oceans into the atmosphere and drops water back to the land as rain, recharging rivers and groundwater aquifers. This cycle repeats over and over.
However, with climate change and variability, population growth in arid regions, and locally limited water resources, the water cycle doesn’t always provide water where it is most needed. Taking a cue from nature, the water industry has developed reliable technology to mimic and speed up the water cycle’s groundwater filtration process to produce water that is available on demand.
Recycled water has been used in communities throughout California and the United States for almost 100 years and its use is growing rapidly in water-stressed areas. With an eye to the future, Oxnard initiated the Groundwater Recovery Enhancement and Treatment (GREAT) program in 1999 to secure additional local water supplies to prevent shortages in the future. This program recognized that reusing water that was locally available was key to a sustainable water supply portfolio and the advantages to Oxnard and our region are many:
- It is a water source that is independent of outside influences, such as the climate, water demands by other cities or regions, and judicial rulings.
- It is dependable, locally controlled and beneficial to the environment.
- For Oxnard, recycled water will decrease the city’s dependence on imported water and provide a reliable source of local water.
- It takes less energy to produce recycled water in Oxnard than to import water from Northern California.
Advanced Water Purification Facility (AWPF)
The City of Oxnard’s Advanced Water Purification Facility is an innovative facility that uses one of the world’s most highly developed purification processes to produce safe and clean water from treated wastewater. Water that is usually sent to the ocean following extensive treatment at Oxnard Wastewater Treatment Facility is instead directed to the AWPF.
- Microfiltration (MF) – A low-pressure membrane filtration process where pressure is applied to push water through a filter with pores that are 5,000 times smaller than a pinhole to strain suspended particles, bacteria and other materials from the water. MF is used in commercial industries to process food, fruit juices and soda beverages; in computer chip manufacturing; and to sterilize medicines that cannot be heated. The filtered water is then ready for the next treatment step.
- Reverse Osmosis (RO) – A high-pressure membrane filtration process forces water through tightly wound layers of thin, plastic sheets. Although the water can pass through, most minerals cannot. RO filters out contaminants, viruses, salts and other materials from the water. RO is also commonly used for desalting brackish groundwater, in kidney dialysis and in the beverage industry. Many bottled water companies use reverse osmosis because of its proven purifying capability.
- Advanced Oxidation with ultraviolet light and hydrogen peroxide (AOP) – Disinfection is provided by UV, a high intensity light similar to extremely concentrated sunlight. UV converts hydrogen peroxide into a disinfectant that destroys any microorganisms and organic materials that might remain in the water after the previous two steps of treatment. This process provides extra assurance that no unwanted contaminants will remain in the purified water. UV is used by hospitals and dental offices to sterilize instruments.
This three-step, multiple barrier process at the AWPF produces an ultra-pure water that can be used to meet any future water supply needs in Oxnard.
At this time, the high-quality recycled water is distributed through its own separate pipeline system specifically built for this purpose. The recycled water pipeline is identifiable by special purple pipes and connections. Initial uses of recycled water include: irrigation of parks, medians, golf courses and athletic fields; watering of agriculture crops; and process water for local industries.
Using Recycled Water Tomorrow
In 2014, new regulations were adopted that allows the injection of highly-purified recycled water into groundwater aquifers. Following testing, development of an operational plan, and regulatory approvals, the water can be pumped out (recovered), treated again, and distributed as potable water. This is known as “indirect potable reuse” or IPR.
To demonstrate this option’s viability for Oxnard, the Water Division has an Aquifer Storage and Recovery (ASR) well test system that includes one ASR well, three monitoring wells, and pumping equipment. The testing phase includes injection of recycled water from the AWPF into the local groundwater basin and after 3-4 months of underground storage, also known as “retention time,” the water can then be pumped back out and then analyzed for water quality. The testing results will be used to develop an operational and water treatment plan for future use as potable water.
This indirect potable reuse project will help reduce reliance on costly imported water, protect our groundwater resources, and provide a beneficial reuse of a scarce resource that would otherwise be discharged and lost to the ocean. The promise of the GREAT program is fulfilled as Oxnard’s water simply becomes One Water.
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Last updated February 16, 2022