An angle stop is the small shutoff valve under a bathroom or kitchen sink that controls water to the faucet or toilet. In St. Louis homes, these valves sit in tight vanity cabinets, damp crawl spaces, and basement utility rooms, and many have been in place for decades. When one starts to seep, the drip is often small enough to miss until the cabinet floor softens, the paint near the base starts to peel, or a stain shows up on the ceiling below.
Find the exact leak point
Before you touch anything, figure out where the water is coming from. A leak at an angle stop usually shows up in one of three places:
- The packing nut, the round nut where the valve handle stem enters the valve body.
- The compression nut, where the supply line connects to the valve outlet.
- The inlet connection, where the valve joins the home's plumbing, often through soldered copper or a threaded pipe.
Each spot calls for a different response. A drip at the packing nut is often the easiest to fix. A drip at the compression nut is usually solved by tightening or replacing the supply line. A drip at the inlet connection, or any crack in the valve body, is a sign that you should stop and get a professional to look at it.
Get the area dry and ready
Dry the valve, the supply line, and the cabinet floor with a clean towel. Set a dry paper towel or small piece of cloth under the valve so any new moisture shows up clearly. Clear space in the cabinet so you can reach the nut without bumping the shutoff handle or pulling on the supply line. A flashlight helps, especially in older cabinets where the valve sits close to the back wall.
Tighten the packing nut carefully
Packing nuts seal the valve stem with a compressible material that can loosen over time from repeated handle use and changes in water pressure. If the drip is at the packing nut, follow these steps:
- Turn the valve handle fully clockwise to shut off the water to that fixture only. Do not use the main shutoff unless the valve will not close.
- Open the faucet nearby to relieve the pressure in the line, then close it again.
- Fit an adjustable wrench on the packing nut, not the handle, and snug it a small amount in the clockwise direction.
- Slowly open the valve, then check the nut with a dry paper towel.
- If the drip continues, shut the valve and make one more small adjustment. Repeat this only a few times.
The main rule is to go slowly. Overtightening a packing nut can crack the nut, damage the stem seal, or make the valve harder to turn later. If the nut is already snug and still leaks, more force will likely make things worse.
Recognize when tightening is not enough
Some valves cannot be fixed with a wrench. Stop and get a licensed plumber to look at the valve if any of these apply:
- The handle is stiff, wobbly, or spins freely without shutting off the water.
- Water seeps from the valve body itself or from a crack near the threads.
- The leak returns within a short time after tightening.
- The valve is corroded, flaking, or discolored where it joins the home's pipes.
- You are unsure which nut you are turning or which way the threads run.
A valve that does not shut off fully is a problem in its own right. If you cannot stop the flow to a fixture, close the main water shutoff before doing more work, and note the valve for repair or replacement.
Check the cabinet again after a day
A slow leak can hide for a day or more before it shows. After you make any adjustment, run the nearby faucet for a short time, then check the valve, the supply line, and the cabinet floor. Look for dampness, a faint film of mineral residue, or a darkened spot on the bottom panel. Repeat the check after a few days of normal use, especially after a laundry or dishwasher cycle, since changes in pressure can reveal leaks that were not active during the first test.
A dry cabinet after several checks is a good sign that the packing nut was the problem. Keep a note of the date you made the adjustment so you can compare it if the valve starts to drip again later in the year.