The ornamental design for an apparatus for treatment of shower water, as shown and described.
FIG. 1 is an upper left front perspective view showing my new design;
FIG. 2 is an exploded upper left front perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a a right side elevational view thereof, the left side being a mirror image thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown in FIGS. 1-7 show magnets, a sleeve that covers the apparatus, internal rifling, a disk, a large diameter set of threads onto which the sleeve is attached, and a smaller diameter set of threads for attachment of the device to a shower head, all of which form no part of the claimed design.