I've always wanted a cast iron cauldron, and someday I'll get one. Though it is the most iconic water tool in some ways, I don't really associate the cauldron with water, probably because I would burn things in it more than I would use it to hold liquids. I do have a small ceramic cauldron, only an inch or so in diameter. I forget where I got it from, but when I want to offer water or other liquid in a ritual, I often use it. It's a good size for solitary practice.
I also have two chalices. Both I got from kitchen goods stores. The first is a dark red crystal wine glass, so dark it looks black unless you hold it directly up to a light. The second I probably wouldn't have gotten if I didn't have the first. It's a very pale pink at the top, a champagne flute, and the stem is a pale green and they fade into each other in the middle. It's not my typical style, but when I saw it I thought it would make a nice contrast to the other, so I would have one for darker aspects and one for lighter.
I don't always make offerings for solitary rituals (excepting Sabbats) so I don't always use a chalice in workings. I used to use them more, but I used to use more elaborate circle castings all the time. The kind where you use the Athame to mix salt into blessed water and consecrate the circle. I think when I was starting out, I needed more ritual all the time, and now I break out the fancy ritual for special occasions, but it isn't necessary for every circle. Perhaps it is a confidence thing, but I don't feel I need the salt and water to purify space, I am more than capable of doing it all on my own. Of course, if I am working something big, or just want that extra zing, I'll go that extra mile.
I have a couple of things I consider tools of water that don't typically get mentioned. The first is a bottle that I store blessed water in. It is one of those green glass beer bottles, the ones with the fancy ceramic stopper hinged to the top with metal. I fill it with water and then bless it myself. Normally it lives on my altar, and is my representation of water.
I also do a lot of water work in the bathtub. Though I haven't consecrated the tub itself, I typically bless the water and sprinkle it with salt. I have also used herbs in the tub as needed (if you don't want bits of herbs floating about, use a teabag of appropriate tea or make your own with a coffee filter tied together). The tub is absolutely my go-to when I am emotionally out of wack and can't seem to pull myself back together.