Recycling Water for Groundwater Use and Drinking Water

Water is a finite resource. We cannot make more of it. The same water on earth today is the same water that was here during the times that dinosaurs roamed.

Southern California’s dry climate with little rainfall requires the need for a sustainable and secure supply for water. With record breaking dry periods, such as the most-recent drought that took place over the course of five years from 2012 to 2017, water agencies throughout California are looking for solutions for maintaining a sustainable drinking water supply. It is more important than ever to become less dependent on  imported water and reduce costly sources of water to support the region’s demand. Dry years forced water agencies to look for innovative and progressive avenues that create local viable supplies of water.

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Advancements in technology, water treatment facilities and innovative thinking have created wastewater recycling and groundwater recharge. This approach to water supply management gives Southern California agencies a feasible option to meet the needs of its commercial and residential customers while preserving groundwater basin levels.

What exactly does wastewater recycling mean? It is a highly sophisticated process that the Environmental Protection Agency describes as “reusing treated (cleaned) wastewater for beneficial purposes such, as agricultural and landscape irrigation, industrial processes, toilet flushing, and replenishing a groundwater basin (referred to as groundwater recharge).” California’s Department of Water Resources describes groundwater recharge as “the augmentation of groundwater, by natural or artificial means, with surface water or recycled water.”

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This wastewater treatment and reuse process is currently being used for both non-potable (not consumable) and potable (consumable) via recharge across the region. Orange County Water District (OCWD) has led the way in developing and implementing a water purification system for indirect potable reuse. Its Groundwater Replenishment System (GWRS) is considered the world’s largest of its kind and serves as a global model for water reuse.

“Wastewater is a resource. That is why OCWD has made a significant investment in implementing and expanding the Groundwater Replenishment System . In fact, by 2023 the GWRS will produce 130 million gallons of water a day. The GWRS creates local water reliability and helps OCWD diversify its water portfolio. These types of projects have tremendous potential throughout California, and beyond. As water managers, we must look at all available options in our region to create long-term water reliability and water reuse should be considered,” shared OCWD General Manager Mike Markus.

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The GWRS takes highly treated wastewater that would have previously been discharged into the Pacific Ocean and purifies it using a three-step advanced treatment process consisting of micro-filtration, reverse osmosis and ultraviolet light with hydrogen peroxide.  In order to simultaneously maintain the groundwater basins integrity that was no longer being sustained by natural recharge, and to satisfy the demands of their ever-growing population, Orange County Water District will  replenish the supply with purchased imported sources as needed. Although the GWRS creates more local water reliability, Orange County Water District is still reliant on other water sources. The GWRS does reduce dependence on other water sources by 30 percent.

GWRS enabled the water district to reduce the need to purchase imported supplies and instead allowed them to recharge their basin with their wastewater that had been extensively treated. Their process is often described as a state-of-the-art production that creates a high quality, local indirect potable supply which is beneficial to all its consumers. Different types of this supply model, albeit smaller in production, are imitated throughout the region.

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Although treatment plants and techniques have become increasingly modified, using recycled wastewater to meet demands is not entirely new. In fact,  according to the Department of Water Resources, it is a technique that has been used for over a century.  During the late 1800s farmers began using wastewater to grow crops and others started using it for landscape irrigation. Investing in infrastructure for these operating systems usually requires a larger upfront cost but provides multifaceted benefits that often offset and surpass the cost. The Department of Water Resources list the following benefits for recycled water:Restores wetlands and marshes;

• Forestalls a water shortage by conserving fresh water;

• Provides additional reliable local sources of water, nutrients and organic matter for soil conditioning;

• Provides drought protection;

• Improves the economic efficiency of investments in pollution control and irrigation projects, particularly near urban areas;

• Improves social benefits by creating more jobs and improving human and environmental health protection.

Water districts understand the public health concerns regarding the use of recycled water, which is recharged in the groundwater basin and later used for potable water. They battle the misperceptions by ensuring quality tests meet and exceed mandatory state and federal regulations for drinking water. With increasing demands and an unpredictable future in California’s climate, building infrastructure for recycling wastewater for groundwater recharge is an option that is becoming increasingly popular to increase local control of water of resources.