Quick Answer:
A leak coming from the packing nut when you operate the valve usually means the packing around the stem is loose or worn. Stop turning the valve, dry the stem, then tighten the packing nut 1/8 turn and retest. If that does not stop the leak, the packing may need replacement or the valve may require service.
Why This Happens
The valve stem has packing material (fibers or a gasket) compressed by the packing nut to seal where the stem passes through the valve body. Over time the packing can dry out, shift or compress unevenly. When you move the handle, the stem rubs and can push water through a loose or worn seal. A sudden leak that appears only while operating the valve is almost always at the packing nut area.
If the leak started right after you reopened the valve, it may be related to movement of old packing—see dripping after being reopened. If the leak began after a recent valve change, consider checking how the new part was installed—see replacement caused new leaks.
Step-by-Step What to Do
1. Stop operating the valve and assess
- Stop turning the handle. Continued operation can make the leak worse.
- Look for where water is coming from—if it’s the small gap around the packing nut or along the stem, proceed with the packing adjustment steps below.
2. Dry the stem
- Use a clean rag or paper towel to dry the stem and packing nut area so you can see active dripping.
- Drying also makes the next test more reliable.
3. Tighten the packing nut 1/8 turn
- Use an appropriately sized wrench. Turn the packing nut only about 1/8 turn clockwise to compress the packing slightly. That small adjustment often reseals the gap.
- Do not force it; stop when you feel a modest resistance. If the nut won’t move, stop—do not apply excessive torque.
4. Retest
- Wipe the area dry again and slowly operate the handle through its normal range. Watch for any new leakage.
- If the leak has stopped, leave the valve for a few hours and recheck. If a tiny leak remains, you may try one more small (1/8 turn) adjustment, but avoid repeated heavy tightening.
5. Next steps if tightening doesn’t work
- If the leak continues after one or two small adjustments, the packing is likely worn and should be replaced or the valve serviced.
- If you can isolate the downstream supply and are comfortable, you can replace the packing. Otherwise, call a professional to avoid damaging the main shutoff.
What Not to Do
- Do not overtighten packing or you will seize the stem.
- Do not use a hammer, heat, or force to try to free a stuck nut—this can damage the valve or packing area.
- Do not ignore a steady leak; long-term leakage can corrode the valve body or make the shutoff unreliable when you need it most.
When to Call a Professional
- The leak persists after two cautious 1/8-turn adjustments and drying/retesting.
- The packing nut is frozen or the stem feels loose or wobbly—signs of internal damage or corrosion.
- You cannot safely isolate the water supply to do repair work, or the valve is the property of the water utility and requires their service.
- Large leaks, rapid loss of water pressure, or visible metal corrosion around the valve.
Safety Notes
- Turn off downstream fixtures before attempting adjustments so you know whether water flow is normal when you test.
- Wear eye protection and gloves to avoid contact with dirty water or debris.
- If the main shutoff is under pressure and water flow is heavy, tightening the packing without isolating the line may not help—consider calling a pro.
- If you must stop heavy leaking and cannot safely fix the valve, contact your water utility or a plumber—do not create an unsafe situation trying to force a repair.
Common Homeowner Questions
- Can I keep tightening until it stops? No. Tightening a little (about 1/8 turn) is fine; repeated or heavy tightening risks seizing the stem.
- Will replacing the packing fix it? Often yes—new packing restores the seal. If the stem or valve body is corroded, the whole valve may need replacement.
- Is this dangerous to leave? A small drip is not an immediate hazard, but ongoing leaks can worsen and make the main unreliable. Have it repaired soon if tightening doesn’t stop it.