I have an old 2 litre and a very old 4 litre, both are turquoise.
Both are tainted but to the best of my knowledge have only ever held water. I have tried to clear the tainting following advice given here but was somewhat half hearted about it and bought a new 2 litre bladder. That is the only size I need nowadays. Both are probably ok for water that you are going to boil and certainly for water to wash in.
I don't need them as water bottles, hot water bottles or pillows so they are going free to anyone who can make use of them. I think the tainting taste can be removed if you are prepared to give it more effort than I did :0)
I would prefer that they went to two different people and younger people in preference to old unless you are older and out of work. (I was once young and short of equipment; now I am old and got more than I can carry)
PM me with preferred size and I'll decide who gets them. In case you can't clear the taint I'll stand the postage.
I'm home for the rest of today. Tomorrow I head into S. Staffs for a couple of days cycle camping and ecclesiastical architecture admiration. I'll post them toward the middle of next week.