Mold in my ink bottle? Now I only pick distilled water.

I always figured tap water was just fine for thinning out my ink mixes. Last month, I made a batch of forest green and added plain tap water. After about a week, I noticed these fuzzy little spots floating in the bottle! It was totally mold, and I was SO annoyed. I read online that distilled water doesn't have the impurities that can cause that. I gave it a go with a fresh mix, and it has stayed perfectly clear for a month now. That ONE success completely shifted how I do things. Now I swear by distilled water for EVERY ink adjustment. It's a simple fix that prevents a BIG headache.