By Ryan Moin, MESM, July 2017


Imagine being told that your utility company was providing your home with water sourced from “wastewater recycling” or water produced by a multi-step purification process often referred to as “toilet to tap.” Would you be alarmed? In Orange County, residents have had purified recycled wastewater in their drinking water supply since 2008, so if you have been to Disneyland in the past nine years, chances are you have already tried some.


Understandably, it can be difficult for people to surmount the psychological hurdles and see the sensibility of incorporating recycled wastewater in the drinking water supply. Some have difficulty accepting its innocuousness, despite the advanced technology used to treat recycled wastewater and the scientific research proving that it is safe to drink.


However, by 2019, wastewater will enter the Pure Water Monterey treatment facility and exit as water that meets or exceeds state and federal drinking water standards. California American Water will be purchasing the water after it enters the groundwater basin, and will supply it to domestic users on the Monterey Peninsula.


Pure Water Monterey Advanced Water Purification Demonstration Facility
The Pure Water Monterey Advanced Water Purification Demonstration Facility

The scientific community and elements of the water management establishment are increasingly embracing wastewater recycling and reuse as a water source to meet domestic and agricultural needs, and to replenish overdrawn groundwater sources. The idea of wastewater reuse is based on the principle that water should be judged exclusively by its physical quality and that its recent history is, for all practical purposes, irrelevant.


Pure Water Monterey is a recycled water project developed by Monterey Peninsula Water Management District and the Monterey Regional Water Pollution Control Agency. It is billed as a practical and cost-effective water resource solution for the Monterey Peninsula and the Salinas Valley. On July 6th, Sustainable Silicon Valley’s Water Team paid a visit to the Pure Water Monterey Advanced Water Purification Demonstration Facility for an informational presentation and tour.

SSV’s Water Team tours the Pure Water Monterey Demonstration Facility

The project will treat four different wastewater sources: wastewater from homes and businesses, wash water used to make pre-packaged lettuce, storm water, and agricultural runoff. The facility is expected to come online in the next two years and will reduce groundwater pumping in the Salinas Valley by up to 2,000 acre-feet annually, while providing up to 3,500 acre-feet of potable water for the Monterey Peninsula.


This project is set against the backdrop of concerns regarding traditional water sources for the Monterey Peninsula. Historically, the peninsula relied heavily on the Carmel River. However, overdraft of the river by California American Water to provide residential water has severely reduced flows, diminishing the resource and threatening unique aquatic and riparian habitats. As the Monterey Peninsula has no connection to the State Water Project or Colorado River water resources, the Pure Water Monterey project has the potential to create a locally based, eco-conscious water source and contribute to water security for the region.


The plant will recycle water from the aforementioned sources, which will first undergo two stages of treatment at the Monterey Regional Water Pollution Control Agency, before arriving at the Pure Water Monterey facility. The water will undergo four treatment steps at Pure Water Monterey before being injected into the Seaside Aquifer.


The SSV Water Team received a tour of the advanced water purification demonstration facility, which showcases the four steps the water will undergo. These include:

  • Ozone treatment: Molecules, bacteria, and organics are broken down into smaller pieces.
  • Membrane filtration: Smaller pieces from step (1) are filtered out.
  • Reverse osmosis: Salt ions are removed.
  • UV disinfection and hydrogen peroxide: This process sterilizes any remaining pathogens. Odor and taste compounds are removed, as well as micropollutants.


The water is then injected into the Seaside Groundwater Aquifer.


Cups for Water Taste Test
Tasting recycled water

The SSV Water Team had the opportunity to do a blind taste-test of the recycled water alongside Arrowhead bottled water. While our team unanimously endorsed the Arrowhead water over the recycled product water, there were no complaints about the latter’s taste. If anything, the recycled water could be described as being more “tasteless” when compared with the bottled water—perhaps due to the absence of minerals that may have been lost during filtration and reverse osmosis.


Pure Water Monterey will be an important project for the people of Monterey and the Carmel River ecosystem. Its success could also serve as inspiration for other communities on the Central Coast and elsewhere in California.