Just Don’t Call It Wastewater

“Everyone talks about the weather, but no one does anything about it,” Mark Twain famously said. It often seems everyone talks about recycling water, too, but too few—especially now with the widespread perception that the drought is over in many places—really practice it.

Twain (after whom a New York golf course is named) might have appreciated what’s happening in Scottsdale, AZ. As this blog post from the Arizona Municipal Water Users Association describes, the city has partnered with 23 private golf courses to help pay for the cost of treating wastewater by reverse osmosis; the water is then used to irrigate the courses. Scottsdale, which is east of Phoenix, has been treating about half its wastewater in this way for nearly two decades, sharing the cost of building and operating the advanced treatment plant with the golf courses.

The advantage for the city is clear—less potable water is used for irrigation. What’s the benefit for the golf courses? Ironically, better water than they would get by using untreated potable water. As the post explains, water the city receives from the Colorado River via the Central Arizona Project is relatively high in salt content, with as much as 650 milligrams per liter of sodium. The treated water (which is blended with CAP water after treatment) has a sodium concentration of about 125 mg/l, which means the courses can use less fertilizer and somewhat less water, and the grass is healthier.

Throughout the area served by the Arizona Municipal Wastewater Users Association, most of the wastewater is now treated and reused: “The name [wastewater] no longer really applies for AMWUA cities,” the post notes. The treated water is used for irrigation, helps recharge the aquifers, is added to lakes and wetlands, and is used for cooling the local nuclear power plant. Although all the water used for irrigation is treated to “Grade A+” quality, meaning that not only are there no detectable disease-causing bacteria, but also that nitrogen compounds have been removed, much of it is treated more cheaply than by the reverse osmosis process used for the golf courses’ water. That process also removes salts, both those present in the wastewater from water softeners and other sources, and from the treatment process itself.