Which measures help reduce water hammer in a cold water supply?

• A. Install air chambers or water hammer arrestors.
• B. Ensure rapid valve closure to minimize surges.
• C. Use long, flexible hoses to absorb pressure.
• D. Install air chambers or water hammer arrestors, ensure proper valve closure, use slow-start appliances, and secure piping.

Answer: (D)

Water hammer happens when moving water is abruptly stopped, creating a pressure surge that bangs pipes and can damage fittings. The most effective way to reduce it is to cushion that shock and smooth out how flow changes. Installing air chambers or water hammer arrestors provides a buffer that absorbs the surge when a valve or fixture shuts off. Controlling how valves close matters because slamming a valve creates a sudden stop, so closing valves slowly minimizes the peak pressure. Using slow-start appliances and fixtures prevents abrupt increases in flow, keeping pressure changes gentle. Securing piping keeps pipes from vibrating and moving under pressure changes, which also helps dampen hammer effects. Relying on long, flexible hoses isn’t a reliable solution on its own and can introduce other issues, so the best approach combines these measures for the most effective reduction of water hammer.