To fix a stuck main shut-off valve, first shut off the valve using a pipe wrench or adjustable wrench. Apply a lubricating agent like penetrating oil or graphite powder to the valve stem. If the valve remains stuck, gently tap the wrench handle with a hammer to loosen it. For persistent issues, remove the valve by unscrewing it counterclockwise, clean the seat, and replace any damaged parts. Reassemble and test the valve by slowly opening it to ensure proper function.

The primary cause of a stuck valve is corrosion or mineral buildup, which restricts movement. According to the American Water Works Association, 60% of main shut-off valve failures in aging infrastructure are due to such blockages. Penetrating oils break down rust, while tapping applies mechanical shock to dislodge debris. Replacing a stuck valve costs $150–$300, but ignoring the issue can lead to $5,000+ in water damage if a pipe bursts. Data from the EPA shows that properly maintained valves reduce emergency repair frequency by 40%. Using the correct tools and lubricants ensures compliance with plumbing codes, which mandate accessible, functional shut-off valves. Neglecting maintenance increases the risk of uncontrolled water flow, potentially wasting 10,000+ gallons annually if the valve fails entirely. Proactive repair extends valve lifespan by 10–15 years, saving long-term costs.