Lago Filler is a job title referring to someone who fills lagoons with water. This is typically done in order to maintain the water level of the lagoon, or to fill it up for recreational purposes. The term Lago Filler can also be used to refer to someone who works with water in other ways, such as cleaning and maintaining lagoons. The crossword solution AGUA (4 letters) is Spanish for water, which is the main element used by a Lago Filler.