The bladder for my North Face Megamouth has started leaking. I had a quick look online to see if it was possible to buy a replacement but can't find anywhere selling the bladder alone and North Face haven't replied to a query if it is possible to get one. One thing I do like in this bladder is the magnet that attaches to the pack to help you stop dragging your end in the dirt, but the small opening for filling makes it awkward to clean. Are there any recommendations for a replacement option? What are the pros and cons of other makes?