I had a UC waterbirth 3 weeks ago, and have a box full of stuff I didn't use. Here's what I did use:
-tarp, inflatable pool, and hose
-2 buckets- 1 for vomit, 1 small one (from my son's sandbox toys) for pee (I couldn't fathom getting out of the pool but didn't want to pee in it, although near the end I did, not wanting to stand up out of the water)- afterwards we used the big bucket to empty the pool
-several towels
-string and scissors for cord
-depends for PP bleeding- much comfier than huge pads and didn't leak once! I wore them for the first 2-3 days before switching to cloth
-popsicles were great during labor, I had my mom stop at the store for them on her way over
-supplies for placenta smoothies- blender, frozen bananas and strawberries, juice or soymilk
-ibuprofen for after birth cramping- that HURT!
Didn't need:
-I didn't have any swelling and only minor (healed within a week) tears, so I didn't end up using the herbal sitz bath, witch hazel, cold packs, etc. that I had gotten for use after birth.
-the Depends totally handled the PP bleeding, so I didn't use the puppy pads I'd bought- we use them as disposable changing pads now
Wish I'd had:
-heating pad for after birth
-bendy straws