The ornamental design for a waterleakdetector, as shown and described.
1. Water leak detector
1.1 is a front perspective view of a water leak detector showing our new design;
1.2 is a front elevation view thereof;
1.3 is a rear elevation view thereof;
1.4 is a left side elevation view thereof;
1.5 is a right side elevation view thereof;
1.6 is a top plan view thereof;
1.7 is a bottom plan view thereof; and
1.8 is a front perspective view thereof as installed in the top bay of an exemplary base structure.
The broken lines in the reproductions illustrate portions of the water leak detector and an exemplary base structure that form no part of the claimed design.