Jetflow offers a pretty simple concept. Turn any water bottle into a reservoir, or use their large bottle with a wide mouth for easy cleaning to hold more water.
The idea came about because they were tired of cleaning bladders, and didn’t like the taste they imparted. The parts and bottle can all be thrown into the dishwasher,
The $30 “Eagle Kit” hydration system includes adapters to fit standard water liter-or-larger bottles (Dasani, Fiji, etc.), a mid-sized bottles (Powerade, etc.) and a large adapter for Nalgene bottles or their own. The hose has a one way valve on the opposite end of the hose that goes to your mouth, letting air into the bottle so it’s not creating a vacuum. The larger $40 “Raptor Kit” includes their BPA-free 35oz bottle and a hose cleaning kit.
They make packs, too. The smaller ones come with the hose kit and are $49.99 and the larger ones include the bottle for $79.99.
They’re made by Ledge, which makes other outdoor and camping equipment.