This page contains information regarding Star Trek: Lower Decks, and thus may contain spoilers.
A power washer was a type of cleaning tool used to remove large amounts of dirt and debris from large structures. Starfleet used sonic power washers during the late 24th century, two of which were stored in a larger docking device.
During a second contact mission to Apergos in 2381, Ensign Beckett Mariner used a sonic power washer to clean soot off at least two buildings in the planet's capital city. In doing so, however, she inadvertently activated an ancient machine that released strange energy, which imbued Commander Jack Ransom with god-like powers. (LD: "Strange Energies")