These do exactly what they say they will. I use one every day in the house. Soft and flexible and no taste. I like these the best because they have a no spill valve, somewhat like a baby bottle nipple. If I drop them on the carpet they don't spill.
http://specializedwaterbottles.com/purist/
Stainless bottles of many designs work perfectly. I have five or six different kinds, at least. The hard plastic Nalgene bottles also work perfectly. There are a number of different ways to make a sports top nozzle on stainless, or hard plastic bottles work. The Nalgene ones have a flip top and a hole big enough to pour it in your mouth.
They all work fine.
Google a few things. They're all on line.