Very true, Jim. But as I said, you can see water is boiling but that won't tell you if chemicals in it will kill you or not. The big risk there would be urban water after a disaster where petroleum or other chemicals could pollute the water.

With a filter I surely wouldn't rely on one that had been stored for 10 years! But that's just me.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman