Yes it is the container! I has the same issue with Fugi water. Anything in a thick plastic bottle

PS the hospital food I was told has some additive because I asked why it tasted strange. It is some preservative like the above answer. It’s not MSG but it’s grainy. I’m not allergic to it, so it’s not MSG, not gluten either, and not soy but the zephyrhills water gives me a bad headache. Same with Aquafina aka Florida toilet water.

Oh my gosh. That explains the zephyr hills headache.

Soy allergies are tricky but it includes monosodiumglutamate or also E341 I think. It is a additive added to food to enlarge your taste buds to make food taste better. Also called umami. It is made from the crystals that is left in the vats the soy sauce is fermented in. These crystals are ground and used as a white salt like substandse in almost all processed foods.