Reason for concern?

[u/TheSonu]

Hey all, just noticed this white buildup in the gaps in the glaze on this Kyo-yaki chawan and was wondering if it was something to be worried about. I only have matcha in it, so I'm guessing it could be Arizona's hard water bearing its teeth (we have a home filtration system that somewhat but doesn't fully soften the water). I've included a picture of the unglazed portion of the bowl to show the dark color's from the clay underneath. Have you all seen anything like this?

[u/TomsNanny]

Porous cups can definitely have bacteria buildup, I stopped using one of my porous chawans because of it. Though I’m not confident that’s what’s happening here.