Monday, May 23, 2011

Tap Water is Not a Naturally Occurring Substance

A couple of recent Skepticality interviews (with environmental engineer Kelly Comstock and environmental toxicologist Shane Snyder) taught me something that may seem obvious, but which changed my mind. Tap water is an industrial product. It occurs nowhere in nature. Water suppliers use natural water to make tap water according to what's healthy for us to drink.

To make tap water, you need to remove a lot of stuff, such as micro-organisms, industrial pollutants, organic residues and mineral particles, perhaps also salt and lime. Then you need to add chlorine to keep the microdaddies down, fluoride to improve people's dental health, perhaps salt and lime to improve the taste of the product. We most definitely don't want to drink pure H2O.

Recent news stories about the occurrence of trace amounts of pharmaceuticals in tap water appear to have been overstated non-news. It's actually been known for decades, and the question is really one of how "trace amounts" is defined. Recent improvements in testing methods allow researchers to observe much lower concentrations of many substances than before. What you really need is a defined limit as to how much of a substance you're willing to accept, which is a toxicological question.

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