Monument Valley • Filling up a portable water tank at the public tap outside the post office in Monument Valley is an exercise in patience. Five or 10 pickup trucks carrying 250-gallon tanks wait in a line around the edge of a dirt lot most summer days, …Monument Valley • Filling up a portable water tank at the public tap outside the post office in Monument Valley is an exercise in patience. Five or 10 pickup trucks carrying 250-gallon tanks wait in a line around the edge of a dirt lot most summer days, …