There is a Legacy version here.


Source Player Core pg. 463
Effects with the water trait either manipulate or conjure water. Those that manipulate water have no effect in an area without water. Creatures with this trait consist primarily of water or have a connection to magical water.

Planes with this trait are mostly liquid. Visitors who can’t breathe water or reach an air pocket likely drown. The rules for aquatic combat (Player Core 437) usually apply, including the inability to cast fire spells or use actions with the fire trait. Creatures with a weakness to water take damage equal to double their weakness at the end of each round.