Why this exists
My bottle always started to smell funny, then taste weird, somewhere between the gym and work. Every single day.
I'd wash it with soap and the funk came right back in two or three days. That's when I learned about biofilm: the invisible layer that builds up inside every bottle and holds onto odor.
The only thing that actually worked was boiling it. I got tired of that. There had to be a better way, so I made one.