This is most likely Gammarus Pulex or "Freshwater Shrimp"
I don't believe they are anything special in terms of working out whether water is potable or not. They tend to prefer slow-moving, highly oxygenated water, but that's about it.
Watch your pee, both frequency and colour.
If your pee is clear, and you are peeing often, you are at no risk of dehydration. May be drinking a bit too much.
If your pee is clear to pale yellow, and you peeing at reasonable interval, this is optimum.
If you pee is dark yellow, strong smell, then you should be drinking more.