Sorry to bring up an old (ish) thread but I have something to say on this.
In my younger days I was puking my guts up after some rides. It turned out I'd found little black bits of mould in my bottles and once I got them clean, I was OK. It was the glucose powder I'd added going off as I wasn't too particular about keeping the bottles clean.
Numerous years of very thorough cleaning after each ride followed.
A couple years ago I read a thread about what folk do when it's early morning and chucking down on the campsite and the inevitable 4am need to pee happens. A regular here suggested using a water bottle and then rinsing in the morning, which I found to be a disgusting thing to do. No ill effects from doing that were reported from the writer though.
I had that dilemma the other week. Early morning, raining stair rods, toilets were closed anyway. What to do? I pondered this question for a good hour or so. Was it sanitary? Probably not. Was I desperate? Damn right I was.
And so the water bottle was used as a urinal. Next morning, gave it a bloody good wash with boiling water and soap and used it for drinking during the next 2-3 days. No ill effects.
Those same bottles are 2 years old and still perfectly fine. Look after them and they'll look after you but they don't need boiling in acid. Bit of a rinse with soapy water and you'll live 😊