Can I use a carpenters level on a 2x4? I have a water level tank I
built for posts, but not sure how I would use it to level ground. It
was a 10 gallon plastic tank with a nipple on the side or bottom. Cant
remember it has been in my shed for awhile now. One of those things I
built one weekend out of some scrap when I was bored.

Make 2, 10 inch posts, set on the ground, if the top of the posts are
level, the ground is level

CarlBoyd