I've tried a bunch of water apps and they nearly all give you the same answer: 8 glasses. But someone small in an air-conditioned office and someone bigger working outdoors in the heat obviously don't need the same amount. That bugged me enough that I built my own. It's called Sippy. It asks about your body, how active you are, your climate and life stage, then works out a daily target — and shows you the breakdown of how it got there, so it's not just a number pulled from nowhere. The bit I'm happiest with: the whole screen is your glass, and it fills up as you drink. Sounds a bit silly, but it's the first time logging water hasn't felt like a chore for me. A couple of things I added after using it myself: - When a reminder pops up, you can tap Sip or Glass rig