When to Treat Water

The rule is simple: if you're not certain it's safe, treat it. The situations that always call for treatment, and how often to rotate what you store.

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You can’t see, smell, or taste most of what makes water dangerous. So the decision rule isn’t “does it look bad?” — it’s “am I certain it’s safe?” If the answer is no, treat it. These are the cases where the answer is always no:

Treat when

Any water from an unknown or open source — stream, pond, rain, unknown tap.
After a boil-water advisory, flood, or loss of water pressure.
Water that’s cloudy, colored, or smells off — settle and filter first, then treat.
Stored water past its rotation date, or that you’re unsure about.

Rotate stored tap water every 6–12 months. Commercially sealed water keeps far longer — mind the date, but it’s conservative.