Feb. 6, 2022

MMWD must increase commitment to creating recycled water

While nearly 70% of the planet is covered by water, only 2.5% is freshwater and only 1% is accessible.

Water reuse, also known as water recycling, is the process of intentionally capturing wastewater, stormwater, saltwater or graywater and cleaning it for a designated beneficial freshwater purpose such as drinking, industrial processes, surface or groundwater replenishment, as well as watershed restoration.

There are two types of recycled water to be used for drinking:

• Indirect potable reuse (IPR) uses an environmental buffer, such as a lake, river or a groundwater aquifer, before the water is treated at a drinking water treatment plant.

• Direct potable reuse (DPR) involves the treatment and distribution of water without an environmental buffer.

In California, only IPR is permitted currently. According to reports, DPR is expected to be permitted by the end of 2023 as well.

Within IPR, there are two primary applications for recycled water. One is for outdoor irrigation, agriculture, industrial and commercial use. The other is recycled water people can drink.

Wastewater travels through sewers and pipelines to community wastewater treatment plants. There, it is either cleaned to a level where it is safe to return it to the environment, such as releasing it in the San Francisco Bay, or cleaned further to be used for non-drinking applications.

If it’s to be used for drinking, it is sent to a water purification facility for additional cleaning. Saltwater and stormwater can also be recycled for drinking.

As a founding member of Marin Coalition for Water Solutions, I believe water recycling is an important option in providing Marin with a sustainable water supply. With water recycling, Marin residents don’t have to rely on outside, potentially undependable sources to meet our needs.

So, is anyone actually drinking recycled water? The answer is yes, they are, and here are some examples:

• Fairfax, Virginia: In service since 1978, this is the longest operating potable reuse project in the United States.

Recycled water is added to the Occoquan Reservoir where it blends with existing surface water. The reservoir supplies water to the Fairfax County Griffith Drinking Water Plant where it is treated to drinking water standards and distributed to approximately 321,000 people.

In drought years, up to 80% of the total reservoir water pumped to the drinking water treatment plant may be recycled water; in normal years, it is less than 20%.

• Wichita Falls, Texas: Because of severe drought in the 1990s, city officials agreed to construct an interim potable reuse facility that purified wastewater and piped it directly to the Cypress Water Treatment Plant, which cleaned the water again before it was distributed to customers.

Since then, Wichita Falls developed a potable reuse system that purifies water and stores it in nearby Lake Arrowhead.

• Monterey: The coastal California city takes wastewater from multiple sources and puts it through a state of the art purification plant that uses six separate stages of purification before it’s ready for customers to drink.

For every 10 gallons of water that are put into their systems, eight come out. Some of that goes to irrigation and non-potable uses. Right now 30% of the water going to the taps is from their plant. By 2024, they expect that number to be 50%.

There are capital expenses in building the infrastructure to do the recycling and transport of the water in Marin. But I think it is an investment in our future security. It must be considered by the Marin Municipal Water District Board of Directors.

The staff at MMWD have done estimates on the costs for additional water supply, including desalination, so these aren’t new ideas. We must keep up the pressure on the board to implement these solutions.

There are 11 recycling projects underway in California. They are managed by water districts who recognize the need to increase their supply, as well as continue prudent conservation.

If only the MMWD was as strategic.

Steve Isaacs, of Greenbrae, is one of the founders of MarinCoalitionforWaterSolutions.com