Lessons Learned

Propel "fitness water" (a flavored water drink made by Gatorade) comes in a fairly interesting bottle that features a twist valve in the cap:

The twist valve was implemented across a lot of Gatorade products because of user feedback (and as everyone knows, focus groups are never wrong), though in practice, it's hard to get out sufficient water without applying significant suction (since there's no way for air to get in).

The twist cap is also prone to leakage, which is important to consider if you reuse the bottle and say, put in your gym bag, which sits in the trunk over a long hot weekend, and as a result, causes your workout bag, clothes, pads, gloves and shoes to smell like sour milk.