As water reuse expands, proponents battle the ‘yuck’ factor
As drought and climate change threaten water supplies, municipalities around the country are ramping up water reuse efforts. But they have to overcome the “yuk” factor.
Many forms of water reuse have long been routine. Water from yard sprinklers, for example, soaks into the groundwater. Or, if it is processed in a treatment plant, it goes into a river or lake, where it’s used again. Municipalities and others often treat a form of wastewater known as gray water to use for irrigation.
But in the world of water reuse, the gold standard is known as direct potable reuse — cleaning wastewater, including sewage, to drinking water standards.
With DPR systems, the water from showers, sinks, and toilets first goes to a conventional treatment plant, where it is disinfected with chemicals and aeration. Then it gets a second scrubbing in a multistage process that first uses a bioreactor to break down nitrogen compounds, then employs microfiltration to clean out particles and reverse osmosis to remove viruses, bacteria, and salts. Finally, hydrogen peroxide is added and the water goes through an ultraviolet light processing, which is supposed to kill any contaminants that are left.
Experts say the water that emerges at the end of this process is so clean it has no taste, and that minerals must be added to give the water flavor. It’s also free of a little-known health hazard; chlorine, often used to disinfect conventional water, can react with organic material in the water to create chloroform, exposure to which can cause negative health effects.