*Informational purpose only*
I believe most non sanctioned grow ops route water hoses up to the area from a local water source or backpack in a reservoir and water and leave it onsite. Filling it occasionally.
Either that or they live out there while it grows.
As for the plants needing water, who knows unless you can see it. Could be soaked still or dry as a bone. Also depends on other plants using the water resource around them.