Do you have to put a cement slab down first or can you just put in on the ground?

Pad

A pad is optimal however, these can be self contained units placed on a level, firm foundation similar to the above ground pools. You can even place them inground. Inground would be expensive putting in a deck and proper access and support. Also depends on the model you get. My model is the 650 waterfall and is best on a porch requires only a 110v 20a dedicated electric line.