Now for some info on my gear. Living in Virginia, the elements were a bit kinder in summer (I've never come home with my hair frozen in Florida). It is quite difficult to decide between runs at 7AM that are 75 degrees and 100% humidity or at 10AM that are 90 degrees and 70% humidity. Obviously staying hydrated and cool in these conditions is challenging.
I have tried a number of hydration options over the years. The "fuel belt" did not work well for me. This is a design with a wide neoprene foam belt that stretches to fit well. Different models come with different sizes and numbers of small bottles on them as well as pockets for gels and MP3 players. However, I kept hitting my arms on the little bottles and did not really feel like it met my needs. I ended up settling on a belt designed for hiking with two 1-liter bottles and a large pocket between that resed in the lumbar area. I found it at Walmart in the sporting goods section for like $10. It suited me well and let me go out for 20 miles, no problem. But it had limitations.
The belt shifted around and twisted on my waist. If the bottles were not balanced in their fluid amounts, they would make the belt shift worse. You could feel the water sloshing pretty easily. The belt was a canvas thing with no padding, so I had to improvise a solution with cut-up pieces of towel and rubber bands. Now in Florida, I was hoping for something new and better.
After much searching, I settled between a Camelbak and products from Nathan Performance Gear. My reservation about the Camelbak was the weight, nearly a pound without any water in it. I was not thrilled with the design and I spoke to some other runners and read reviews that were not stellar. The Nathan packs, on the other hand, weighed a mere 6 ounces and were universally reviewed well. For whatever reason (popularity??) They proved hard to find and most retailers were sold out. Road Runner Sports eventually turned up with an HPL 20 for under $70 shipped. I ran with it for the first time last week on an 8 mile run in the 75 degree 100% humidity.
It was great. Aside from me leaving too much air in the water bladder resulting in minor feeling of sloshing, I barely noticed it. The hose extends to right in front of your chest with an easy to use bite valve (note: pull the valve out AND bite it to get forward flow). Two relatively capacious pockets up front held my gel packs and keys, but I could have easily added a cell phone or more.
The heat and humidity made me run more slowly than I would have liked, but the water made it so that I still felt pretty darn good by the end of the run. I highly recommend the Nathan 20 to anyone looking for a backpack-style water source for running any significant distance. I was road-running, but I am sure it would be great on trails as well.