Surge of energy in the opposite direction caused by suddenly stopping water moving through a hose or pipe

• A. Siphon
• B. Turbulence
• C. Water hammer
• D. Backflow

Answer: (C)

Water hammer is the pressure surge that happens when moving water is suddenly stopped, causing the water’s momentum to push back and generate a pressure wave through the hose or pipe. This occurs because water has inertia and the system can’t stop instantly; a rapid valve or nozzle closure sends a shock wave toward the source, creating a backward energy pulse. The result is a transient spike in pressure and can cause loud banging, hose whip, and stresses on fittings. This is distinct from a siphon, which is a gravity-driven flow mechanism; turbulence, which is irregular, chaotic flow patterns; and backflow, which is a sustained reverse flow rather than a brief pressure surge.