Bay Area cyclist Alison Chaiken doesn't like backpack hydration systems. The plastic bladder is easy to puncture, difficult to clean and expensive to replace. The backpack is annoying to cyclists. Alison came up with this homebrew bite valve hydration system that uses PET soda bottles and other readily available parts.
Gents, Alison is single. She's a physicist who likes working with large powered tools and she reads Cyclelicious. My heart swoons.
For more DIY bike stuff, see Bike Hacks.