The term "water thief" refers to three devices – one ancient and two modern.A water thief is a synthetic rubber fitting that attaches to an unthreaded faucet on one end and a common garden hose on the other. It is commonly used to fill fresh water tanks in recreational vehicles when a threaded hose bib is not available.A water thief allows firefighters to break down one larger line into several smaller ones, each with independent control of water flow at the valve.