Recycled wastewater is as safe to drink as potable water. According to Stanford University engineers, it may even be less toxic than many of the water sources we consume daily.
William Mitch, a senior author of the Oct. 14 study, said potable reuse waters undergo much more extensive treatment than conventional drinking water, so we expected them to be cleaner, in some cases, than traditional drinking water. Nature Sustainability published 27 studies comparing conventional drinking water samples with water purified from wastewater, also known as potable reuse water. "In some cases, however, the quality of the reused water, particularly with experienced filtration methods, the treated water, was comparable to groundwater, traditionally considered the highest quality water."
Drinking water sources are becoming scarcer as the public and utility companies struggle to meet demand.
In the United States, there are several potable reuse systems in operation. Since the 1970s, the Orange County Water District has operated the world's largest water recycling facility. It is planned that all wastewater in Los Angeles will be recycled by 2035. As part of their drinking water supplies, Aurora, Colorado, and Atlanta, Georgia, use potable reuse water.
Due to decades of drought, however, recycling wastewater has become as common as recycling La Croix cans. Especially in drought-stricken areas of the west, water utilities are struggling to find reliable water sources. Colorado River water and snowmelt from the Sierra Nevada have dried up. Utility companies instead rely on potable reuse as a reliable water supply, one they already own and manage.
"Aside from securing water supplies, there are additional benefits," said Mitch, Stanford Engineering and Stanford Doerr School of Sustainability professor. "If you don't import water, there's more water for ecosystems in northern California or Colorado." The wastewater is cleaned up, so the beaches of California are not polluted.
Additionally, recycling water costs a lot less and uses less energy than extracting salt from seawater.
As a result of treatment, potable reused water is cleaner than water obtained from pristine rivers. It is often negligible, or no treatment of wastewater dumped into waterways by someone upstream, as opposed to what happens in potable reuse systems. Deep cleaning isn't possible with conventional wastewater treatment plants. The result is that many organic contaminants, such as chemicals found in shampoos and medicines, end up in drinking water.
In potable reuse treatment plants, regulators demand more extensive treatment. In addition to removing harmful pathogens, such as viruses and amoebas, Advanced filtration, ozonation, and biofiltration can also be used to remove other contaminants.
By pushing water at high pressure through a small filter, osmotic filter treatment removes even sodium and chloride from the water. The process cleans wastewater as much as groundwater, the gold standard, if not more.
EPA regulates a wide range of chemicals in order to protect people from toxic drinking water. Scientists have yet to identify or categorize some of the stuff floating in our water.
Water from various sources was applied to hamster ovary cells to determine their toxicity since they behave similarly to human cells. As compared to untreated cells, Mitch and his colleagues examined whether cells slowed or stopped growing. "Ideally, we would have picked up both chemicals measured by the EPA and those that weren't," Mitch said.
Less than 1% of the harm to ovary cells is caused by EPA-regulated compounds.
Mitch says that even if we include all these unregulated compounds that we've been focusing on, they account for only about 16% of the total. As a result, we're not necessarily focusing on the relevant contaminants."
Disinfection may be the culprit. Whatever your tap water source, it will carry residual disinfectant to prevent pathogens from growing. Chlorine reacts with chemicals in the water and converts them into something else, which may be killing the hamsters.
THM, we know this to be called here at The Portable Well Company
EPA regulates some disinfection by-products, but not all. "Our study suggests that the toxicity of government-regulated by-products may not be that important."
The team plans to investigate whether other side effects of disinfecting water could cause toxicity. Every product is formed when disinfectants are mixed with pesticides, proteins, or organic materials.
Mitch emphasizes that disinfecting water is a balancing act between killing pathogens and minimizing harmful by-products. Without disinfection, we'd die of cholera and other waterborne diseases.
" There is no way we can eliminate all contaminants, as it would be costly and probably unwarranted from a health standpoint," he said.
No matter what you do, Mitch warned, don't fill your fridge with bottles of water. Plastic compounds have migrated into bottled water, resulting in the plastic taste.
"Everything has stuff in it, but reused water is as good as tap water, which is pretty good."
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