Replacement bladders from Karrimor at Field and Trek 1 ltr £7, 2 ltr £8 and 3 ltr £9!
http://www.fieldandtrek.com/karrimor-hydration-bladder-787045
I have used these as Camelback replacements and at under half price are a bargain. Noticed the bite is not as good as the Camelback, so I swap the hose and bite over to the new bladder.
camelback has a life time warranty…got mine replaced after 9 years of use 🙂