You mean a CamelBak?
Bring a small camelbak. Stick a tiny handheld fan in there, the ones with the folding blades. You can also fit some sunscreen, wipes, whatever else you need in there. To top it off, you can securely slide a harry potter wand into the gap where the drinking tube comes out at the top.
Camelbak Hydration Pack, cheap, amazing quality, multiple colors, perfect fit - Bag
Camelbacks are my favorite festival hydration packs! HydroBak Hydration Pack 50 oz https://www.amazon.com/dp/B01L8JENFO/ref=cm_sw_r_cp_api_glt_i_T8G1V08CJKC6450WQSYG
I second this. I have one for running. Sit's higher on your back, and doesn't make swishing noises because of the water pouch. Has small pockets to put keys and stuff in. https://www.amazon.com/CamelBak-HydroBak-Reservoir-Hydration-Graphite/dp/B01L8JENFO/ref=psdc_3400551_t3_B01L8QTUJ6
Just get a CamelbaK,