Hose bibbs and hydrants allow outdoor access to running water. Hose bibbs and sillcocks are built into the exterior of a building to connect hoses for landscaping, washdown, and facility maintenance. Yard hydrants are subterranean water supply lines that allow year-round water availability in outdoor spaces. Water is supplied to outdoor areas through wall hydrants, which are mounted on the outer walls of buildings. They include a key that prevents unauthorized entry to the fire hydrant. During the winter months, outdoor faucet covers are used to keep the faucets from freezing owing to low temperatures and chilling wind chills.