Excavating the Hole

• 1). Excavate a hole in the ground larger than your planned cistern. The bottom of the cistern hole should be undisturbed ground, so dig the last 6 to 12 inches by hand, not with excavating equipment.
  
  
• 2). Build a concrete form out of 2 inch-by-6 inch scrap grade lumber. For our example, we will discuss an 8 foot-by-8 foot square cistern that is 6 feet tall. Build a square frame, and set the frame into the hole so that it rests securely on the bottom of the hole. Make sure the top edge of the form is level all the way around. The cement is leveled to this wood form.
  
  
• 3). Push the U-shaped pieces of rebar into the ground, so that the bottom of the "U" points upward. Position these steel reinforcing rods around the perimeter of the cement floor so that they extend upward 3 to 4 inches higher than the concrete forms that frame the 6-inch thick floor.