If you're going light and fast, strap on Fox's Low Pro Hydration Pack.
•Sleek low profile design for an unrestricted feel
•Front zippered pocket compartment to pack essential items
•Lightweight mesh shoulder straps for breathability and comfort
•Hydrapak 1.5 Liter reservoir with slide top large opening for easy filling/cleaning
•45 angle Bite Surge Valve High flow with a twist shut off
•Breathable mesh back panel allows air to circulate and ventilate