Faucet Packing Nut: How to Tighten It and Stop Stem Leaks

Water dribbling out from under the handle every time you open an old faucet or outdoor spigot almost always traces back to one small part. The faucet packing nut squeezes a ring of packing material around the valve stem, keeping water from escaping up the stem while still letting it turn. When that packing dries out or the nut loosens, water finds its way out around the handle. In most cases, a quarter turn of a wrench stops the leak in under five minutes.

The quick fix works like this: open the faucet slightly so the stem is under pressure, then snug the packing nut clockwise an eighth to a quarter turn at a time until the drip stops. Turn the handle through its full range to make sure it still moves freely. If tightening does not stop the leak, or the handle becomes hard to turn before it stops, the packing itself is worn out and needs to be replaced.

Packing nuts show up on compression-style sink faucets, tub and shower valves in older homes, hose bibs, laundry tub faucets and many gate valves. Newer cartridge and ceramic disc faucets rely on O-rings instead, so if your faucet is a single-lever design from the last few decades, the leak is probably coming from a different part.

What a Faucet Packing Nut Does

Inside a compression faucet, the stem threads down to press a rubber washer against a seat, which shuts the water off. The stem has to pass through the top of the valve body to reach the handle, and that opening needs a seal that can tolerate constant rotation. That seal is the packing.

Traditional packing is a graphite or fiber string, sometimes impregnated with a lubricant, wrapped around the stem. Some faucets use a pre-formed packing washer, a rubber or fiber cone, or a combination of a washer and an O-ring. The faucet packing nut sits on top of this material. As you tighten it, it compresses the packing against the stem and the inside of the bonnet, closing the gap.

Over years of use, packing wears, dries and shrinks. Each turn of the handle grinds away a tiny amount. That is why an old spigot that has been fine for a decade can suddenly start weeping from the stem, and why a slight tightening often brings it back.

Packing nut vs bonnet nut

Many faucets have two nuts stacked on the stem. The larger lower one is the bonnet nut, which holds the entire stem assembly in the valve body. The smaller upper one is the packing nut. On some designs, the two are combined into one piece. Tightening the bonnet nut will not compress the packing; you need the upper nut. If you only see one nut, it likely serves both purposes, and the packing sits beneath it.

Tools and Materials

• Adjustable wrench or open-end wrench sized to the nut
• Second wrench or pliers to hold the valve body steady on hose bibs
• Screwdriver to remove the handle screw
• Rag or tape to protect chrome finishes
• Graphite or non-asbestos packing string, or a matching packing washer
• Small pick or flat screwdriver to remove old packing
• Silicone plumber’s grease
• Replacement seat washer and screw while the faucet is apart
• A faucet repair kit for compression faucets, which often includes packing washers, seat washers and screws

How to Tighten a Packing Nut

Start with the simplest fix. In many cases, you do not even need to shut off the water for this step.

1. Remove the handle if needed. On many sink faucets, the handle covers the packing nut. Pop off the cap, remove the screw and lift the handle away. On most outdoor spigots, the nut is visible just under the handle.
2. Open the faucet a little. A slightly open valve puts the stem under pressure and makes the leak visible, so you can tell when it stops.
3. Tighten in small increments. Turn the packing nut clockwise an eighth of a turn. Check for leaking. Repeat until the drip stops, usually within a quarter to half turn.
4. Brace the valve. On a hose bib, hold the spigot body with a second wrench so you do not twist the pipe inside the wall.
5. Test the handle. Open and close it fully. It should turn with normal effort. If it binds, back the nut off slightly.

How tight is too tight?

The goal is the lightest tension that stops the leak. Overtightening crushes the packing, makes the handle stiff and accelerates wear, and on brittle old brass it can crack the nut or bonnet. A good rule: if the handle becomes noticeably harder to turn before the leak stops, the packing is spent, and more torque is not the answer.

How to Replace Faucet Packing

When tightening fails, replace the packing. It is a cheap, satisfying repair.

1. Shut off the water. Close the supply valve feeding the faucet, or the main shutoff for an outdoor spigot. Open the faucet to drain remaining pressure.
2. Remove the handle and the packing nut. Unscrew the faucet packing nut counterclockwise and slide it up and off the stem.
3. Dig out the old packing. Use a pick or small screwdriver to pull out old string or the worn packing washer. Clean the stem with a rag; a little fine steel wool removes light corrosion.
4. Wrap new packing. Wind packing string clockwise around the stem, the same direction the nut tightens, so the nut drags it inward rather than unwinding it. Three to five wraps is typical. If your faucet uses a packing washer, slide the new one into place instead.
5. Reinstall the nut. Thread it on by hand, then snug it with the wrench just enough to compress the packing.
6. Restore water and test. Open the supply slowly, open the faucet and check the stem. Tighten slightly if it weeps.

While the faucet is apart, consider pulling the stem completely and replacing the seat washer at the bottom. If the faucet also drips from the spout, that washer is worn. A matched washer and brass screw costs very little and finishes the job in one visit.

Troubleshooting Stem Leaks

• Leak returns within weeks: the stem may be scored or pitted, which tears fresh packing. Replace the stem if it shows grooves.
• Leak only when the faucet is wide open: some stems have a back seat that seals against the packing area when fully open. Packing replacement usually fixes it.
• Water leaks from the bonnet threads rather than the stem: the bonnet nut or its washer is the problem, not the packing.
• Spigot leaks inside the wall when the hose is attached: a frost-free sillcock may have a cracked tube from freezing. That needs replacement, often by a plumber.
• Nut will not budge: apply penetrating oil, wait 15 minutes and try again with the valve body braced. Do not force a corroded nut on a fragile old fixture.

Packing Nuts on Outdoor Spigots and Valves

Outdoor hose bibs see the most packing leaks because they sit in sun and cold and are often opened hard. The fix is identical, but always brace the spigot body so the pipe connection inside the wall does not loosen. In freezing climates, disconnect hoses before winter so trapped water does not damage the valve.

The same packing principle appears on older gate valves and some main shutoffs. Tightening a gate valve packing nut a small amount can stop a weep around the stem. Be cautious with main shutoffs: if the valve is very old, aggressive turning can cause a leak you cannot stop without shutting off water at the street. If you are unsure, have a plumber service it.

Costs and When to Call a Plumber

Packing repair is about as cheap as plumbing gets. Packing string or a packing washer typically costs a few dollars, and a compression faucet repair kit generally runs under 15 dollars. Your main investment is 15 to 30 minutes.

A plumber handling a stem leak on a faucet or spigot usually charges a service call plus a small parts cost, often in the range of 100 to 250 dollars depending on your area and access. Call one if the shutoff valve will not close, the stem or valve body is cracked, the leak is inside a wall or ceiling, or the fixture is a tub or shower valve behind tile where a mistake could damage finished surfaces. For an exposed faucet or spigot, though, a wrench and a few wraps of packing usually solve it for years.