PURE WATER MONTEREY ADVANCED RECYCLING PROJECT

Pure Water Monterey (PWM) is an advanced water recycling project originally initiated in 2014. The recent expansion of PWM was jointly developed by Monterey One Water, the Monterey Peninsula Water Management District, and the Marina Coast Water District. Completed in October of 2025, PWM now supplies the Monterey Peninsula with 60% of its drinking water from a clean, safe, and sustainable source.

Pure Water Monterey ends our dependence on the Carmel River and the Seaside Basin as the sole sources of drinking water for the Monterey Peninsula. The project reduces water use to help meet regulatory orders and enhance water supply reliability through diversification. It also reduces stress on the river’s migratory Steelhead population.

By supplying over half of the Peninsula’s total annual needs, it will help fulfill the drinking water requirements for new housing, jobs, growth, and drought mitigation for decades to come.

The PWM project is the first to utilize not only wastewater, but also stormwater, food industry processing water, and impaired surface waters. It uses proven and reliable water recycling technology and provides environmental protection and replenishment of the groundwater supply.

PWM’s purified water complies with or exceeds strict state and federal drinking water standards. The purification process includes:

• Ozone Pre-Treatment: Ozone, a powerful disinfectant, is added to the water to destroy bacteria and other pathogens.
• Membrane Filtration: The water passes through very fine hollow fiber membranes (about 1/300 the width of a human hair) that remove particulate matter, protozoa, and some viruses.
• Reverse Osmosis: The water is forced through a special membrane at high pressure to remove impurities such as dissolved salts, viruses, pesticides, and most organic compounds.
• Ultraviolet/Advanced Oxidation: The water is exposed to ultraviolet light, in combination with hydrogen peroxide, to sterilize and eliminate remaining organic compound traces.
• Groundwater Replenishment: After purification, the water is so pure that PWM must stabilize it by adding calcium and removing carbon dioxide. It then travels approximately 10 miles via pipeline and is injected into the Seaside Groundwater Basin. Injection wells are intentionally placed to ensure the water resides in the Basin for a minimum of two months before the water purveyor, California American Water, utilizes its extraction well to deliver the water to its customers.

This technology has been proven safe and reliable throughout the United States and the world.

For more information on this project, please visit: purewatermonterey.org.