Can he?

Despite being described as a guy that can run pretty fast, he is still too slow for runing on water.

with his hammer he could probably

I doubt it. Has there ever been such a feat in Thor's history?

he's not that fast. Not that he needs to since he can, you know, fly.

i doubt it ..his speed is too inconsistent

Though he can reach escape velocity and even more speed using his hammer to fly, Thor's running speed is not sufficient for running on water.

I've never seen him do it.

if need be....

If you could fly, I don't see how that would even be a concern.

Why would he run on water when he can fly?