Primals have the ability to create, out of nothing other than force of will, the substance that they are a Primal of. They do not, however, have the ability to alter the state of matter that this substance is in, that depends on the environment in which the substance is created in.
For instance, if an Earth Primal were to create earth in an environment hospitable to humans, than the rock would be in a solid rock like state. If, however, an Earth Primal were to create earth in an environment of over 700 degrees Celsius than the rock would be in a liquid magma like state. The same principles apply to the other primals, including Water.