The ornamental design for a water-flow regulator, as shown and described.
FIG. 1 is a front perspective view of a water flow regulator showing the new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is an exploded view thereof.
The broken line showing in FIG. 8 is included for the purpose of illustrating elements of the water-flow regulator and forms no part of the claimed design.