The amount of water on Earth has remained constant for millions of years. When ocean water evaporates it comes back as rainfall and the cycle continues. With less than one percent of the world’s water available for human use, the U.N. warns that half the world population will face water scarcity by 2030.1 Accelerated by climate change, population growth and the scarcity of fresh water resources such as rivers and lakes, especially in the arid regions of the world the need for additional water supplies is critical. One viable resource is recycled or reclaimed water.
But what is recycled or reclaimed water? The US EPA defines water recycling as reusing treated wastewater for beneficial purposes such as agricultural and landscape irrigation, industrial processes, toilet flushing, and replenishing a ground water basin (referred to as ground water recharge) 2. In this instance the terms recycled and reclaimed are used synonymously.
Water recycling is most commonly described as either "unplanned" or "planned." An example of unplanned water recycling is when one city draws its water supplies from a river that has received wastewater discharge from the cities upstream. Water from these rivers has been reused, treated, and put back into the water supply numerous times before the last downstream user receives it. Planned projects are those that are developed with the goal of reusing recycled water for some beneficial purpose.2
The history of recycled water is an extensive one. For nearly 100 years, highly treated reclaimed water has been used in the United States.3 In San Francisco recycling water dates back to the early 1900’s when partially treated wastewater and groundwater were used to turn the Golden Gate Park area from barren sand dunes into the lush garden spot you see today. Los Angeles County's sanitation districts have provided treated wastewater for landscape irrigation in parks and golf courses since 1929.4
There are many places to see examples of water reuse outside the US as well. Israel treats 80% of its sewage (400 billion liters or 1 trillion gallons a year), and 100% from the Tel Aviv metropolitan area is treated and reused as irrigation water for agriculture and public works.5 The second largest waste reclamation program in the world is in Spain, where 12% of the nation's waste is treated.6 And as Australia continues to battle the 7–10-year drought, nationwide, reclaimed effluent is becoming a popular option. Two major capital cities in Australia, Adelaide and Brisbane, have already committed to adding reclaimed wastewater to their dwindling dams.
There are also some innovative systems that you can view yourself that are closer to home. The EcoCenter at Heron’s Head Park is one of only two buildings in San Francisco that treats its own wastewater. Going beyond conventional treatment, the processes at the EcoCenter involve irradiation and the incorporation of a constructed wetland for further purification.7 You can sign up for a free tour by clicking here. Another tour you can take is at one of the SFPUC wastewater treatment plants. For information on when the next tours will be given follow the link. With California being squeezed dry by drought, we should all look for ways to utilize all the water resources we have. Recycled water could provide one potential way to offset the large water demand of Californians.
1. Monks, Kieron. From toilet to tap: Getting a taste for drinking recycled waste water. CNN World, 1 May 2014. Web. 8 Oct. 2014
2. Water Recycling and Reuse: The Enviromental Benefits. US EPA Region 9, n.d. Web. 8 Oct. 2014
3. Sustainable Solutions for a Thirsty Planet. Water Reuse Association, n.d. Web. 8 Oct. 2014
4. Reclaimed Water. Wikipedia The Free Encylopedia, 30 Sept. 2014. Web. 8 Oct. 2014
5. Rabinovitch, Ari. "Arid Israel recycles waste water on grand scale." Reuters Africa, 14 Nov. 2010. Web. 8 Oct. 2014
6. Lidman, Melanie. "Israel is the world's leading waste water recycler." The Jerusalem Post, 6 Aug. 2010. Web. 8 Oct. 2014
7. The EcoCenter at Heron's Head Park. Port of San Francisco, n.d. Web. 8 Oct. 2014
8. Diagram of Municipal Wastewater Treatment. 2002. Ontario Ministry of Agriculture, Food and Rural Affairs. Sewage Biosolids - Managing Urban Nutrients Responsibly for Crop Production. Web. 8 Oct. 2014