What level should you evolve evee to vaporeion on pokemin red?

To evolve Eevee into Vaporeon in Pokémon Red, you need to use a Water Stone. You can find a Water Stone in the game, and once you have it, simply use it on your Eevee to trigger the evolution. There is no specific level requirement for this evolution, as it is solely dependent on the use of the Water Stone.