I think PLA is water soluble and maybe not so great from an FDA standpoint. I'm working on some water bottle caps and printed them from Taulman Nylon 680. It's a little tougher to print (than PLA) and not as flexible as HDPE (what most water bottles are made from), so it doesn't seal (cap to bottle) as well, and print layer sealing can be tricky too. FWIW...