Do you prefer your water bottle to be made of metal, plastic, glass, or something else? Straw or no straw? How big would you want it? Should the bottle taper down in the bottom, or do you think the sided should stay vertical? Are any of you one of the few people who would like that weird rectangular bottle? Or maybe one of those squishy fold up ones for travel? No handle, flip up handle, mug style handle, or little loop?
Note that I am not affiliated with any water bottle company


20 ounce or 600mL (about the same), insulated, and easy to clean.
I like the Zojirushi, but the rubber parts get mouldy quick. Even if you clean it a couple times a day, people say no, you got to clean it more. No, I’m not cleaning the thing several times a day to keep it food safe. That’s just a losing battle.
Stanley makes a nice one, too (and green, so, bonus) and while it’s got a lot of complex moving parts, it’s very easy to clean with brushes. Mine fell wrong and the trigger popped out and there was so much mould inside, it was nasty. There’s no way to disassemble this part, but also, nothing in there touches the water. Still gross. I just threw it in the trash (it was unfixable anyway).
That’s WILD! Zojirushi makes good stuff, I love my rice cooker. But cleaning water bottle DAILY or it moulds?! I have a couple yeti bottles I use every day and bring everywhere and I soap-clean them uhhhhhh… sometimes. I just rinse my water bottles every so often, and wash my coffee bottle with soap every couple days.
I think I soap-wash my water bottles a few times monthly, and I’ve never had mould on them, ever!
Yeah, I dunno. I thought it it was just mould, it would wash off. I’ve taken some pretty harsh chemicals and scrubbers and they don’t give any. But the black dots that form on the rubber gaskets when they’re exposed to moisture weirds me out. If it’s not mould, even discolouration would be strange.