Here’s the thing nobody tells you before your first camping trip: clear water is not the same as safe water. Giardia is a parasite that lives in lakes, streams, rivers, and springs — and you cannot see it, smell it, or taste it. According to the CDC, it can also show up in places like swimming pools, wells, and even public water supplies. The water can look absolutely pristine and still be full of it.
So what actually happens if you drink it? The Mayo Clinic explains that a Giardia infection can take weeks to clear up — and even after the parasites are gone, you can be left with lingering stomach problems. The CDC notes that not all medicines that treat Giardia work for everyone, which means getting infected isn’t a guaranteed quick fix. It’s the kind of thing that can genuinely ruin a trip, a week, or longer.
The good news is this is completely preventable. The CDC says the best way to kill Giardia in water is to boil it. If boiling isn’t possible, filtering and then disinfecting the water is another solid option — and with that method, both steps matter. One step alone may not be enough. Either way, the rule is simple: if the water came from a natural source like a lake, spring, or river, treat it before you drink it or use it to prepare food. Every single time, no exceptions.
The single most important takeaway: never assume natural water is safe just because it looks clean or is moving fast. Always boil it, or filter and disinfect it, before drinking.