The ornamental design for water meter, as shown and described.
FIG. 1 is a side view of a water meter in accordance with the design;
FIG. 2 is a top plan view of the water meter in accordance with the design;
FIG. 3 is a side view of the water meter in accordance with the design;
FIG. 4 is a perspective view of the water meter in accordance with the design;
FIG. 5 is a top plan view of the water meter in accordance with the design;
FIG. 6 is a side view of the water meter in accordance with the design;
FIG. 7 is a perspectve view of the water meter in accordance with the design; and,
FIG. 8 is a perspectve view of the water meter in accordance with the design.
The broken line showing of structural features is included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design.