The Runlite 10K belt from Amphipod has all the bells and whistles:

• 2-bottle hydration belt has easy-access, squeeze-and-release snap-in flasks; each Hydraform quick-release flask holds 10.5 fl. oz. of liquid
• Remove the bottles and use the belt as a breathable, minimalist waistpack for running, walking or travel
• Reposition the bottles/flask modules elsewhere to add hydration to just about any other strap measuring 1.5-2 in. wide
• Hydraform bottles have Jett-Lock™ caps with a squeeze-and-release high-flow design, ergonomic spout and self-sealing valve; spout locks down to stow the bottle leak-free
• Flasks are BPA-free and dishwasher-safe
• Integrated, expandable XL AirFlow pack holds everything you need on your run, including a large phone, nutrition, keys and other essentials like chapstick
• Internal divider creates a moisture-resistant compartment
• Durable, adjustable 1.5 in. webbing belt hugs the hips and supplies stay-in-place comfort and stability; belt clasps with a low-profile buckle
• Bottle modules can be positioned anywhere on the belt for personalized comfort and access, and additional bottles and modules (not included) can be added to increase capacity
• Flasks can be oriented either vertically or horizontally according to your access preference