1. In a pitless well adapter installable in a well casing having a wall defined by an interior cylindrical surface and an exterior cylindrical surface, and having: an opening in said wall communicating with a discharge pipe, and a drop pipe extending downwardly within said casing below said opening, said adapter comprising in combination: a casing fitting, said casing fitting disposed to be provided in sealing engagement with said exterior surface of said casing and attachable to said discharge pipe, a drop fitting attachable to said drop pipe and engageable with said casing fitting through said opening to provide closed tubular communication from the interior of said drop pipe to the interior of said discharge pipe and to support said drop fitting and drop pipe from said casing fitting, said drop fitting attachable to a lift-out member, said adapter characterized by an actuator for providing positive engagement of said drop fitting with said casing fitting and for providing positive disengagement of said drop fitting from said casing fitting, said actuator comprising in combination: a cam member having two ends, said cam member hingably connected by pin means to said drop fitting to rotate with respect to said drop fitting on a predetermined horizontal axis, said cam member having at one of its ends two cam surface portions contactable with portions of said interior surface on the opposite side of said interior from said opening to first force said drop fitting toward and against the side of said interior opposite to the portions contacted, and to force said drop fitting into engagement with said casing fitting and then to maintain engagement of said drop fitting with said casing fitting, said cam member being disposed to partly straddle a portion of said drop fitting when in said first position to provide said two cam surface portions at least partly disposed on opposite sides of said portion of said drop fitting, a control member attached to said cam member intermediate said two cam surface portions and extendable upward in said casing, said cam member having at its other end at least one cam surface portion contactable with a portion of said interior surface on the same side of said interior surface as said opening to positively disengage said drop fitting from said casing fitting in response to actuation of said control member.

8. A pitless well adapter for a two-pipe jet pump water supply system comprising a casing fitting and a drop fitting which includes an actuator, said casing fitting being adapted for fluid-tight attachment to a tubular well casing around an aperture in said well casing, and having pressure and suction recesses adapted for fluid-tight connection to pressure and suction pipes extending horizontally from said casing fitting, said drop fitting having pressure and suction conduit necks which fit fluid-tight into said pressure and suction recesses, said drop fitting being adapted for connection to pressure and suction drop pipes, said actuator having a cam which (a) straddles the body of the drop fitting, (b) is hinged thereon with a pin, (c) has four contact surfaces the first two of which are shaped to press against the inside wall of said well casing opposite to said casing fitting and the second two shaped to press against the inner wall of said well casing opposite to the first two, said actuator also having a control cable attached to said cam between said first two contact surfaces and extending upward to a handle, and a spring extending from a crank pivot on said cam to an anchor fixed to the body of said drop fitting which constantly applies a torque on said cam, said spring torque being sufficient to insert said conduit necks into said conduit recesses when said conduit necks are aligned with said conduit recesses, said control cable being used to apply a torque on said cam, opposite to that applied by said spring, to withdraw said conduit necks from said conduit recesses when removing said drop fitting.

12. A pitless well adapter for shallow well and submersible motor pump water supply systems comprising a casing fitting and a drop fitting which includes an actuator, said casing fitting being adapted for fluid-tight attachment to a tubular well casing around an aperture in said well casing and having a recess adapted for fluid-tight connection to a delivery pipe extending horizontally from said casing fitting, said drop having a conduit neck which fits fluid-tight into said recess, said drop fitting being adapted for connection to a drop pipe and having two bosses, one above and one below said conduit neck, said actuator having a cam which (a) is hinged on the body of said drop fitting with a pin, (b) has three contact surfaces, the first two of which are shaped to press against the inside wall of said well casing above said pin opposite to said casing fitting, and the third contact surface shaped to press against the inner wall of said well casing opposite to the firSt two contact surfaces, said actuator also having a control cable attached to said cam between said first two contact surfaces and extending upward to a handle, and a spring, extending from a crank pivot on said cam to an anchor fixed to the body of said drop fitting, which constantly applies a torque on said cam which said spring torque being sufficient (1) to press said bosses against the inside wall of said well casing to provide rigid support for said drop fitting, and (2) to insert said conduit neck into said conduit recess when said conduit neck is aligned with said conduit recess, said control cable being used to apply torque on said cam, opposite to that applied by said spring, to withdraw said conduit necks from said conduit recesses when removing said drop fitting.