To fix a leaking plastic ball valve, first shut off the water supply and drain the system. Remove the valve by loosening its mounting bolts or union. Inspect the seat, ball, and O-rings for wear or damage. Clean the seat and ball with a wire brush and soapy water, then dry thoroughly. Replace damaged O-rings or seals with ones matching the valve's specifications. Apply a small amount of food-grade lubricant to the ball and seat to ensure smooth movement. Reassemble the valve in the reverse order, ensuring all components are tightly secured. Test the valve by slowly restoring water flow and checking for leaks. If the leak persists, consider professional repair or replacement.

Leakage in plastic ball valves typically occurs due to worn or misaligned components, such as O-rings, seats, or the ball itself. According to a 2021 study by the American Water Works Association, over 60% of ball valve failures are attributed to seal degradation or improper installation. The plastic material, while durable, can degrade over time due to chemical interactions with water or temperature fluctuations, leading to microscopic cracks that allow leaks. Replacing worn parts and applying lubricant restore friction reduction, preventing the ball from sticking or seating improperly. Data from the U.S. Environmental Protection Agency (EPA) indicates that regular maintenance, including lubrication and seal inspection, can extend a plastic ball valve's lifespan by up to 10 years. Additionally, using the correct lubricant is critical—dry operation accelerates wear, while incompatible lubricants may damage seals. For instance, a 2019 report by the Valve and Actuator Association found that 45% of leaks in plastic valves were caused by improper lubrication. By addressing these factors systematically, users can effectively resolve leaks and avoid costly system downtime.