The ornamental design for a watertreatmentdevice, as shown and described.
FIG. 1 is a top, front and left side isometric view of a water treatment device showing our new design;
FIG. 2 is a bottom, rear and left side isometric view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a rear elevation view thereof;
FIG. 7 is a left side elevation view thereof;
FIG. 8 is a right side elevation view thereof;
FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 3; and,
FIG. 10 is a cross-sectional view taken along line 10-10 of FIG. 3.
The broken lines shown in the drawings are for the purpose of illustrating portions of the water treatment device and form no part of the claimed design.