I thought I smelled bleach in my water bottle

I have 2 water bottles. I have to drink a lot of water each day as I have a medical condition that requires me to drink a lot of water to feel somewhat normal. I put the larger of the two in the refrigerator overnight Tuesday evening. On Wednesday, I thought my water tasted funny, but brushed it off. "Oh I just haven't brushed my teeth yet." "Oh I just drank chocolate milk." Etc. Later that day, I caught a whiff of bleach. I immediately stopped drinking it. I got a chlorine testing kit today. The first photo is from the water bottle I keep on me at all times. Clear, 0ppm chlorine. The second photo is from the bottle left overnight in the fridge, slightly yellow, 0.5-1ppm. They are both hand-washed with the same dish soap, and the water is from the same filtered source. The only difference is that one was out of my sight for 12 hours. The only other person with access to my water bottle was my roommate. I have no proof that she intentionally put bleach in my water bottle, so I'm stuck in this lease with a person who probably tried to poison me until September.