From Toilet to Tap (Almost)

Orange County is turning wastewater into drinking water to mitigate effects of future droughts and keep up with population growth.

Orange County is located in southern California and is highly susceptible to water shortages and droughts, but that’s not stopping people from moving there. The population is expected to grow by another ½ million people by 2020.

So what did Orange County do? The Water District came up with an ambitious plan, known as the Groundwater Replenishment System to convert wastewater into drinking water. The result is a state-of-the art treatment plant that takes in gray-water and pumps out pure water that exceeds federal and state drinking water standards.

How does it work?  An Orange County resident flushes the toilet and the water flows through a network of pipes leading to the treatment plant. The water goes through a purification process that involves microfiltration, reverse osmosis, and UV light and hydrogen peroxide treatment. About half of this newly purified water is then pumped into the ground to create a barrier between freshwater aquifers and intruding seawater.  The other half is piped to lakes in Anaheim where it filters through the ground and percolates into aquifers that are pumped for drinking water. Not exactly toilet to tap, but a good use of grey-water in a place that’s in serious need of more H2O.

What are the benefits?

The Orange County Groundwater Replenishment System is:

Energy Efficient - It takes ½ the amount of energy as bringing water from Northern California.

Cost-Effective - It costs less than imported water.

Reliable - The plant currently services 144,000 families per year with the ability to accommodate twice as many if needed. This reduces dependency on external water sources, and mitigates the effects of future droughts.

Sustainable - Rather than simply treating and dumping wastewater into rivers or the ocean (as is practiced in most communities) the water can be continually recycled and re-used.


Orange County is a successful, innovative model for other communities around the world.  As fresh water becomes increasingly scarce and the population continues to grow, we’ll need more creative solutions like this to ensure everyone has access to the lifeblood of our existence.


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