So to answer the question: your water has white stuff in it because you are fancy and live on a planet made of rocks. It’s not toxic. It’s not a sign of alien colonization. It’s just nature’s way of telling you that your hydration journey comes with a side of geology.
Next time you see those floating specs, just imagine they’re tiny, stubborn celebrities refusing to dissolve for your convenience. Give them a stern look, take a sip, and remember: you’ve had weirder things in your mouth. Cheers!