Without my hydration backpack, don't know if I could have made it through the highway-turned-into-a-parking-lot connecting Sevierville, Pigeon Forge, Gatlinburg, TN, one late afternoon last summer!
High-90's F. temperature, blazing sun, and bumper-to-bumper traffic moving slower than a man can walk. The garish "attractions" locally had just dismissed the thousands of young tourists and their parents who frequent that entertainment industry, and I was caught up in that quagmire.
No chance to reach for a water bottle; pulling off the highway meant questionably getting back on. All in the heat of eastern Tennessee; humidity supplied perhaps by the TVA lakes.
Hydration helps prevent heat stroke. The ability to take a drink at any time can be important, in a situation like that; actually, sound health any time, especially in hot ambient temperature.
My bladder-and-pack at the time was the lowest-cost one on Target's shelves; worked fine; have had to replace the bite valve once (REI has the part). Turned ON by the user biting the valve at the hose tip.
Since, have obtained a jacket with a built-in bladder pouch and hose hole (Joe Rocket Ballastic Adventure).
That said, that's one way to stay hydrated (bladder pack). Not the only way. For health's sake, good idea to find one; hydration pack is convenient and practical when riding, in my experience.
And, oh. You're supposed to CLEAN these things?