If you want to get yourself the ability to carry around some fresh water, then you're going to have to get yourself a shovel. You need a Canteen, and this can only be obtained by having this tool to dig out of the ground a bug that has the materials we need.
To get a Shovel in Grounded, we're going to need to have an Acorn Shell. Acorns can be found at the oak tree, but you will need to be careful because the place is crawling with some prtty mean spiders! If you want to fight them, then make sure you've got a pretty good weapon with you. However, in the early game, you are likely better off just avoiding them all together. If you have Arachnophobia, now would be the time to play with your safe mode settings.
At the very least, you're going to need to bring a Hammer with you. This is required to break open the Acorns, so don't leave without it!
Either get on top of something, or look around the sky for the big oak tree with the red leaves on it. That's where we need to go to find the Acorns we need.
Make your way to the tree, and try to avoid any bugs along the way. You will eventually reach the base, and see a bunch of roots running throughout the ground. Look for Acorns that have fallen from the tree, take out your hammer, and then smash them open.
Collect all the pieces that break off from it, we will likely need some of it later. For now, we really just need one shell for the recipe. We will also need two Sprig and one Woven Fiber.
Once you have your shovel crafted, you can then start looking for Grubs! These are very useful because they have the materials required to make the Canteen. For more on them, check out our How to get Grub Hide guide!