Good point. Activated charcoal should deal with *most* of the organics, but it does nothing for heavy metals, for example.<br><br>It's not just roadway runoff to consider. <br><br>Agricultural runoff from this part of the country is normally chock full of all kinds of pesticides, herbicides, and nitrates/other fertilizer compounds. There's a huge spike in the ambient levels in our rivers everytime it rains upstream of the sampling points. Drain the wetlands... wait, we already did that to over 98% of them in this part of the country...<br><br>In other parts of the country, mining runoff can be bad for you. Specifics vary, but heavy metals are highest on my list of concerns. It's hard-to-impossible in some parts of Colorado to be certain that the stream one obtains water from is not being laced with staggering amounts of heavy metals from abandoned mines. There is potentially more immediately lethal runoff from certain types of mining operations, but these - like cyanide leaching operations - are usually pretty well contained these days and the most usual conditions that might lead to significant leakage are the same conditions that would tend to greatly dilute the effluent.<br><br>Other than distilation or reverse osmosis, there are no GOOD solutions to heavy metal contamination. Exchanging aluminum for heavy metals, as several filters do, scares the bejabbers out of me - the cure may be as bad or worse than the problem.<br><br>I'm neither anti-ag nor anti-mining; these are just additional things to consider. Practically speaking, one is unlikely to be in dire straits for water in this part of the country and even if so, if the water didn't numb or irritate the mouth/throat (chemicals), it's probably not gonna incapacitate/kill one. <br><br>And by similar reasoning, a few days drinking lead-laced water is probably not going to cause any long-term or irreversable problems. Play the odds - but know what they are. Long term exposure to either circumstance is another story, of course.