Water snake : A common North American colubrine snake (Tropidonotus sipedon) which lives chiefly in the water.

Water snake : Any species of snakes of the family Homalopsidae, all of which are aquatic in their habits.

Example:


Taxonomy
water snakes, adults, Photograph, Texas, snakes, Blotched Water Snake, Carl J. Franklin, Dallas Fort Worth, Worth area, Juveniles, dorsal coloration, females, give birth, specimen, Tarrant County, diamond back, species, Reproduction.

Defination from the web:
Water snakes lack venom, but they can defend themselves by delivering a series of rapid bites while smearing feces and musk onto anyone attempting to capture them. ... Blotched Water snake (Nerodia erythrogaster transversa) ...