Would you like some sparkling clear sewer water with your meal?

Posted on March 3, 2008

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glass of waterA new program in Orange County has the locals squicking out over a supposed “toilet-to-tap” program. The program takes treated sewer water, runs it through the same reverse osmosis process that bottled water companies use to purify their artesian (or tap) water, and then injects it into a deep aquifer that provides water for Orange County. The idea is to recycle as much of the water as possible and, in the process, reduce the water needs of a very arid and highly populated region of the country, southern California. The problem is that a lot of locals are going “ewwwwwww!” at the process of drinking water that was once in someone’s toilet.

What these residents don’t realize is that nearly every drop of water they’ve ever drank was once someone’s, or something’s, toilet.

In every respect, the Earth’s biosphere is a marvel of recycling. Plants convert carbon dioxide and sunlight into energy and oxygen. Animals eat the plants (and other animals) and breath the oxygen. And all living things expells wastes into the environment, including people. In our case, our respiration expels carbon dioxide, we sweat as a means of internal temperature control, and we excrete urine and feces. It’s a pretty basic physics or chemistry calculation using really big numbers to determine that every time we inhale, we probably inhale some small number of atoms (< 10) that were exhaled by someone famous 10 years ago or longer. Similar calculations can show that some amount of the water we drink would have once been part of someone else's sweat, or of cow urine, or fish feces. It's almost guaranteed by the laws of probability.

But it's actually simpler and more direct than that. According to the Municipal Water District of Orange County (MWDOC), the county gets half of its water from Northern California and the Colorado River. Counting just four major towns or cities above the Colorado River Aqueduct along the Colorado River (Las Vegas, St. George, Green River, and Grand Junction), the number of people whose treated sewage is dumped into the river is about 2 million. Which means that the people of Orange County are already drinking water that came “toilet-to-tap” by way of the Colorado River.

All water is fundamentally contaminated by things that make people sick. Bacteria, heavy metals, molds, dead plants and animal bits, feces, all of it is in every drop of untreated water. This is, in fact, the very reason that every drop of water we drink is filtered and chemically treated in water treatment plants – to make the water safe to drink in the first place. It’s also the reason that you hear about people being told to boil all their water after a flood backs up sewage treatment plants – boiling kills off the dangerous bacteria and breaks down the viruses that make us sick with diseases like giardiasis and cholera.

It’s interesting that the MWDOC is re-injecting the treated water into the aquifer – that’s not necessary, and it adds an expensive step to the process. It would be cheaper, and probably safer, to connect the treated sewer water directly to the drinking taps. That way you don’t run the risk of dissolving too many minerals into the water and the water wouldn’t have to be treated yet a third time when it’s pulled out of the aquifer.

I understand why many residents of Orange County would go “ick” when thinking of drinking water that once contained feces or urine – they’re ignorant of the fact that they already do. And drinking bottled water doesn’t fundamentally change the fact that the water that’s been reverse-osmosis treated still was once drank and excreted by any number of people and other animals before it was bottled for their consumption. But don’t worry – the United States has one of the best water treatment systems in the world, so while you can’t set yourself apart from the natural world and the “ickiness” therein, you can drink your sparkling clear sewer water secure in the knowledge that it’s safe to drink.

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