This article was taken from the September 2011 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
HOW WE TESTED
We tested filtered tap-water samples using a WaterSafe City Water Test Kit for pH levels, water hardness (dissolved mineral parts-per-million -- PPM), chlorine and nitrate. Supplied by Thames Water from a kitchen tap, water was filtered once, as per manufacturers' instructions. For the dirty-water filters we used the same kit to test samples from a London pond. Each filtered sam- ple was tested for lead and pesticides and we accepted the manufacturers' published results for bacteria and virus removal.
Tadpoles were fished out manually. We used humans for taste tests.
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