What size wiring for water heater?

Currently running wire for appliances/outlets in the Bambi II. I have dedicated circuits with 12/2 wire for the AC, microwave, and refrigerator.



Can I run 14/2 for the water heater? I am not even sure if I will have an electric water heater from the get-go but I want a line for it when/if I do.



Thanks!



Ben