Sometimes a plastic Scotch-Brite pad and a little dish soap will work wonders also. Half of the fun is cleaning them.I got some brushes on amazon that are specifically for cleaning bottles (came with a few different sizes to fit various bottle necks). Warm water w/ dove soap has worked well for me. For tougher ones, I'll soak in vinegar for awhile (I haven't had to do more than 12 hours but also haven't tried less than 12 hours so...). Once I cleaned a bottle I found on the beach on site- put some sand in/mixed with ocean water, put my thumb on top, shook the bottle for a little, rinsed a few times & it worked well. Hope this makes sense/helps!