A patch of land that develops pools of water after a rain storm would not be considered a "wetland," even though the land is wet. Wetlands have unique characteristics: they are generally distinguished from other water bodies or landforms based on their water level and on the types of plants that live within them. Specifically, wetlands are characterized as having a water table that stands at or near the land surface for a long enough period each year to support aquatic plants.

Thanks, Sarah, yeah, technologically, it cannot be defined as a real wetland if it is too small.

However, the constructed wetland can be various sizes, from the size of a house block to large regional systems. In highly urban areas they can hard edge form and be part of a streetscape or forecourts of buildings.

Swales, basin, something like that i think.