A Necessary was an outdoor privy, or toilet. Not only did it provide convenience, it also allowed for the centralized collection of waste. The Necessary demonstrates George Washington's awareness of the importance of sanitation on his plantation.  Human waste was deposited in large wooden drawers below the seats.  The drawers were removable, and the water could be recycled as fertilizer in the gardens.   

Today there are two restored necessaries at Mount Vernon -- located just outside the Upper and the Lower gardens.