We sometimes put soapy water in our sensory table. We often wash dishes or just play with the water. We also like to wash the babies (well, baby dolls). The kids get great joy out of this activity. We provide lots of washcloths and large towels so the babies can be washed, dried, and wrapped up in a nice, warm towel. They usually get fed at some point after this, too, and then put to bed.
Our school has special babies for washing. Yup, they live in a crate in the supply room labeled, “Babies for Washing.” Why? Because babies with movable limbs get water inside that’s difficult to get out and that eventually gets mildewed. Our washing babies are either sealed or they are old enough that we don’t care much what happens to them. While we’re washing babies I put our regular classroom babies out of sight so the kids aren’t tempted to add to the collection of bathing beauties.
The tricky thing, whether it’s dishes or babies, is that other things will migrate to the sensory table. It’s helpful to decide in advance what you’re willing to allow so you’re not caught off guard. My personal feeling is that if I can clean it up and there’s no harm to be done by letting them try, I let them. But things that might rust, mildew, or dissolve I don’t allow. You’ll have to decide if you can stand painty water from hands that were just at the easel; I don’t have a problem with it. You have to wash and bleach the dolls at the end of the day anyway, so what’s a little paint?