If you purchase an independently reviewed product or service through a link on our website, Rolling Stone may receive an affiliate commission. The number one rule of attending festivals ? Besides knowing exactly what stage your favorite artist is playing (and when) it’s staying hydrated. And while there’s no shortage of water packs you can bring inside, the options tend to fall into two camps: aggressively practical or aggressively ugly. Some sit on your back and add too much extra bulk, others