The ornamental design for a portable waterfilter, as shown and described.
FIG. 1 is a front, top, and right side perspective view of a portable water filter showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is an enlarged top plan view thereof;
FIG. 5 is an enlarged bottom plan view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a left side view thereof; and,
FIG. 8 is a referential perspective view showing exploded state thereof.
The features shown in broken lines in the drawings depict portions of the article that form no part of the claimed design. The dash-dotted lines denote the boundary of the claim and form no part of the claimed design.