How often should valves in a water distribution system be exercised?

Exercising valves in a water distribution system is essential for maintaining their functionality and preventing issues such as seizing or corrosion. Exercising refers to the act of turning the valve fully open and then fully closed, which helps ensure that they operate smoothly when needed and allows for the detection of any problems before they arise in emergency situations.

Recommending that valves be exercised at least annually strikes a balance between ensuring their operability and not overburdening maintenance schedules. Annual exercise helps to confirm that all equipment remains in good working condition, addresses any buildup of corrosion or debris, and ensures that the valves can be relied upon during system emergencies or repairs.

The other options, while having their own merits, do not reflect the best practice for valve maintenance. Exercising valves every month could lead to unnecessary wear and tear, while exercising every two years may not be frequent enough to avoid potential failures. Relying only on the valves being exercised when malfunctioning ignores proactive maintenance and can result in system vulnerabilities when they are needed most.