Well, most obvious solution would be something like a drinkers helmet:
But jokes aside, what is an effective way to carry water when training for a marathon or just casually running long-distance?
A comparable question has been asked, but I wonder if there are other ways than a camelback (I own two, but they are quite big) to carry water when running.
I've seen camelbak-type packs (like this one), bottleholders of various types (usually hand/arm holder or belt, like the one @michael linked to), or even runners carrying plastic water bottles by hand. Possibly the most comfortable solution is not to carry water, but to have someone else carry it for you - hydration stations at marathons come to mind.
The best solution is highly subjective - some runners don't mind carrying things by hand, while others might find even a small camelbak to be chafing/uncomfortable. In the end, the runner is constrained by the amount of water that he/she wants to carry, personal comfort, and the amount of money that he/she is comfortable spending. The possibility of reuse for other activities like biking or camping can be a consideration in selecting a solution as well.
Nathan makes some amazing hydration products that are specialized for distance running. I found the Minimist to be the best of their camleback-like products. It only weight 6.5 oz when dry, holds 50oz of liquid and has enough pockets for fuel for a 4 hour run. The cavity that holds the bladder is a bit bigger than the bladder and you can use that space to put extra fuel in it. The pocket in the front is also big enough to slip an iphone into it if you like music. I've used this on many runs and found it to be the best over my camelbacks. It does not hang very much on your shoulders as the weight is distributed through the use of the side straps.
They also make some of the water-bottle holders as well. If you are going to carry a water bottle, I reco getting one that has a least a small pocket on it. This will allow you to carry a gel or a small amount of fuel as well.
I would just get a smaller camelbak. Honestly, people drink more than they need. If you're running efficiently, you don't need that much hydration. If I'm running a marathon, I'll skip by most of the hydration stations, I don't think more than 500ml is really necessary (maybe 1L if you're larger and a profuse sweater).
If you're interested in not carrying water or carrying smaller quantities, you could be creative with your running routes.
Find a neighborhood, running track or path where you can park your car to retrieve water. By running short loops or out-and-back patterns, you can either simulate a race by getting water every two miles or, what I prefer, which is to carry small quantities of water and run longer laps in between stops. A plain water bottle works in either case. You can take a few sips or carry one and replace it as needed.
This has advantages of not requiring any additional gear and allowing you to simulate the water availability during the race.
