The ornamental design for a watering can with a knee pad and knee pad containment chamber, as shown and described.
FIG. 1 is a top-down isometric perspective view of the watering can with a knee pad and knee pad containment chamber, displaying a knee pad containment chamber at the bottom of said watering can and a first side mounted tool holding chamber.
FIG. 2 is a side elevation view thereof;
FIG. 3 is the opposite side elevation view thereof;