I've really gained a lot of knowledge about bike touring on this trip.  Things have really changed from trips I took with my parents in the early 1970's when hydration and attention to electrolytes were addressed with a water bottle or two and a bag of gorp (peanuts, M &Ms and raisins).  I had stocked up on electrolyte tabs on the advice of a neighbor who is a cyclist and carried 2 water bottles.  Our SAG is available at 20 mile intervals with water for refills as well as snacks with lots-o salt, sugar and protein ( peanut M & Ms, jerky, cheese sticks, fresh fruit and all manor of chips, cookies, things most of us would never eat if we weren't loosing water and electrolytes due to the exercise.)   I was feeling dehydrated the first week or so of the trip even though I thought I was drinking enough, and took the advice of my cycling sisters and picked up a Camelback, below.  It has saved the day!  The water is stored in a bladder (yes, really!) in the back with a tube that you can avail yourself to while riding, thus creating more and consistent opportunities to get that water in.  Some people use Gatoraid in theirs, and I recently tried some iced coffee which had the added caffeine boost - those miles just flew by!  At any rate, I love my Camelback and hear that it was invented by an EMT who got the idea from the I fluid concept.