What is the white residue that gathers on top my water bottles?


I have this water bottle that I use at home which I use constantly. I refill it with tap water frequently but every time I open the cap, I see this white residue gathered . What is that and is it safe for me to use that bottle again?

In: Chemistry

Hi there. Guessing you live in a hard water area. What you’re seeing is probably a calcium buildup. If you make coffee, you’ll see the scaling on any interior rings or where water disperses.

Just keep washing it out.

Hard to tell, but it’s likely water that evaporated, leaving behind minerals present in the water. Could also be mold but that has a very different appearance. And really shouldn’t ever happen unless you’re not washing it at least every few days. And you really should wash it once a day.

It’s probably just your water being too hard. That means that it has a lot of calcium and magnesium. When it precipitates out it leaves those behind. It’s safe to drink.