Method of fabrication of collapsible storage tank

1. A collapsible, flexible storage tank capable of holding a liquid material, including:

a sheet of flexible, moisture impervious side wall material being a polymer with internal reinforcing synthetic fibers;

at least one opening for receiving a fitting to fill and drain the tank;

joining seams wherein edges of the sheet of material are joined, the seams extending completely around a circumference of the tank in a spiral orientation wherein at least some of the seams are characterized by a butt joint configuration constructed by locating ends of the sheet of material against one another so that inner edges are butt up against one another and a length of flexible, moisture impervious material being constructed of the same material as the side wall material overlapping the butt joint and sealed to the sheet of material, such that any liquid that leaks into the internal reinforcing fibers has no leak path out of the tank; and

closing seams wherein the side ends of the storage tank are sealed, wherein only two or less joining seams encounter a closing seam at each end of the tank, requiring only two or less areas of liquid impervious seals of three or more layers of material at each end.

2. The collapsible, flexible storage tank as set forth in claim 1 , wherein the length of flexible, moisture impervious material is attached along an outside surface of the storage tank.

3. The collapsible, flexible storage tank as set forth in claim 2 , further including a sealing tape along and covering the butt joint on an inside surface of the tank.

4. The collapsible, flexible storage tank as set forth in claim 2 , further including a second length of flexible, moisture impervious material located along and sealed to an inner surface of the storage tank and covering the butt joint.

5. The collapsible, flexible storage tank as set forth in claim 2 , including a filler material located between edges of the sheet material along and within the butt joint.

6. A collapsible, flexible storage tank capable of holding a liquid material, including:

a sheet of flexible, moisture impervious side wall material being an ethylene based polymer with internal reinforcing synthetic fibers;

at least one opening for receiving a fitting to fill and drain the tank; and butt seams wherein edges of the flexible sheet of material are joined together in the same plane in a butt joint configuration using an overlapping piece of the flexible, moisture impervious sealed material being constructed of the same material as the side wall material over the top thereof, said butt seams extending completely about a circumference of the tank in a spiral orientation such that any liquid that leaks into the internal reinforcing fibers has no leak path out of the tank.

7. The collapsible, flexible storage tank as set forth in claim 6 , including a piece of sealing tape on the internal side of the butt joint.

8. The collapsible, flexible storage tank as set forth in claim 6 , further including a second piece of flexible, moisture impervious sealed material located along an inner side of the seam.

9. The collapsible, flexible storage tank as set forth in claim 6 , further including a flexible, filler material located between edges of the flexible sheet of material in the butt seams.

10. The collapsible, flexible storage tank as set forth in claim 6 , wherein only two or less spiral seams encounter a closing seam at each end of the tank.