Which option describes a water thief?

• A. Gate valve
• B. Water thief
• C. Wye
• D. Siamese

Answer: (B)

In firefighting hydraulics, a water thief is a short section of hose or piping used to take water from a source (like a hydrant or standpipe) and feed it into another line or pump. The idea is to “steal” water from the main supply to supply a second engine or a relay pump without having to rely on additional large sources. This is different from a gate valve, which simply starts or stops flow; a wye splits one line into two; and a Siamese combines two lines into a single larger discharge. The water thief’s purpose is specifically to tap into a source to supply another line or pump, hence its name.