With practice, and be prepared to spill for quite a while, judging by how many of these exist (quite a few also just recommend to use a funnel): https://www.wi

With practice, and be prepared to spill for quite a while, judging by how many of these exist (quite a few also just recommend to use a funnel): https://www.wikihow.com/Pee-in-a-Bottle-(Women) https://www.wikihow.com/Pee-in-a-Bottle-(Women) https://www.rei.com/blog/hike/girl-talk-peeing-in-the-backcountry https://www.rei.com/blog/hike/girl-talk-peeing-in-the-backco... https://www.wikihow.com/Pee-in-a-Bottle https://www.wikihow.com/Pee-in-a-Bottle https://www.tripsavvy.com/can-women-pee-in-a-bottle-backpacking-1766192 https://www.tripsavvy.com/can-women-pee-in-a-bottle-backpack... https://www.ozmo.io/how-can-a-girl-pee-in-a-water-bottle/ https://www.ozmo.io/how-can-a-girl-pee-in-a-water-bottle/ (and many, many more) It certainly doesn't seem anywhere near as easy as just [using] a water bottle.