The ornamental design for a bathwaterbarrier, as shown and described.
FIG. 1 is a rear elevational view of a bath water barrier showing my design;
FIG. 2 is a front elevational view of the bath water barrier shown in FIG. 1;
FIG. 3 is a top view of the bath water barrier shown in FIG. 1;
FIG. 4 is a bottom view of the bath water barrier shown in FIG. 1; and,
FIG. 5 is a side perspective view of the bath water barrier shown in FIG. 1.
The broken line showing bottom surface is included for the purpose of illustrating a portion of the bath water barrier that forms no part of the claimed design.