It was a case of mistaken identity. I was working in my studio and opened the lid of the pill container filled with mixed black gouache. Finding it, as usual, too thick to use, I picked up my distilled water bottle to add a few drops. Reminder to self - make sure that what you think you pick up is actually what you pick up!
Two very similar bottles at my fingers. Two very dissimilar contents.
My black gouache mixture became very sanitary - and quite unusable - with one squeeze of the wrong bottle. It was laughable, but it reminded me of the potential consequences of inattention in my former life as a food microbiologist. Then, pouring from the wrong chemical-filled (and identical) flask could have been truly disastrous. Thankfully, I live to err again.