Hi Jamie and welcome to the forum.
I don't know what the pros do but if it were me I would use a post hole digger and dig a few holes around the perimeter to see how high the water table is. If the holes don't fill with water you are home free. I guess another, and probably easier way would be to drive a tough pipe, like iron, into the ground. Pull it out to remove the cores, then put it back in the ground. You can fashion a dipstick of something to check the level of water in the pipe. You would have to let it sit for a while so the water level stabilizes before checking.
Happy New Year.
Al