The ornamental design for a waterbox for dehumidifier, as shown and described.
FIG. 1 is a perspective view of a water box for dehumidifier showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is another perspective view thereof, in an alternate configuration; and,
FIG. 9 is another perspective view thereof, in an environment of use.
The broken line showing of a water box is included for the purpose of illustrating portions of the article and forms no part of the claimed design. The broken line showing of a dehumidifier is included for the purpose of illustrating environmental structure and forms no part of the claimed design.