A slow drip outside looks harmless, and two of the three causes honestly are small jobs. But a hose bib that soaks the siding or the foundation bed all summer wastes real water, and the third cause — the split pipe — leaks into your wall cavity every minute the faucet is open. So start by watching where the water actually comes from.
Dripping from the spout, faucet off. The rubber washer that seals against the valve seat is worn, cracked, or loose on its screw. This is the most common outdoor faucet leak of all, and it's the same basic failure as a leaky faucet indoors.
Wet around the handle when the water is on. The packing — a ring of string or rubber around the stem, compressed by the packing nut — has shrunk or worn. Water sneaks up the stem threads and out around the handle.
Dry outside, but you hear or find water inside while the faucet runs. You likely have a frost-proof sillcock: a long faucet whose actual valve sits a foot inside the warm wall. If water was trapped in that tube over winter, the tube splits lengthwise. The faucet works fine and doesn't drip when off, because the valve is indoors — it only sprays inside the wall while running. Check the basement or crawlspace near the faucet while someone turns it on.
Most hose bibs have an interior shutoff valve on the pipe feeding them, usually in the basement or crawlspace a few feet from where the pipe exits the wall. Close it, then open the outdoor faucet to drain what's left. No dedicated valve? Use the main shutoff for the house. Every repair below assumes the water is off and the line is drained.
Replace the stem washer for a spout drip. Loosen the packing nut under the handle and unscrew the whole stem assembly out of the faucet body. At the inner end you'll find a rubber washer held by a small screw. Swap in a new washer of the same size — flat and beveled styles aren't interchangeable, so match what came out — snug the screw, and thread the stem back in. Turn the water on and test.
Tighten or repack the packing nut for a handle leak. Start embarrassingly simple: snug the packing nut, the hex nut right behind the handle, by about an eighth of a turn. A quarter of all handle leaks end there. Still weeping? Turn the water off, back the nut off completely, and wind fresh packing string around the stem, or fit a new packing washer if that's what your faucet uses. Reassemble and tighten until the leak stops — but no further.
Replace a split frost-proof sillcock. This is a swap, not a patch; solder and sealants won't hold a split tube. From inside, unscrew the sillcock from its fitting — most thread out as one long unit. Measure it before you buy: common lengths run 8, 10, 12, and 14 inches, and the replacement has to match, because the valve seat sits at the far end of that tube, inside the wall. Thread the new unit in, reconnect, and test with someone watching the wall cavity.
One more oddity: if water sprays briefly from the little cap on top of the faucet when you shut it off, that's the anti-siphon vacuum breaker doing its job — or wearing out. A second or two of spit is normal. A steady spray every time means the breaker insert under that cap needs replacing, a cheap part that twists out by hand on many models.
Leaving the hose attached all winter. This is what splits frost-proof sillcocks. The tube is designed to drain itself empty after every use, but a connected hose traps the water inside, and trapped water freezes and bursts the tube. Disconnect hoses in the fall — it's the whole point behind preventing frozen pipes in the first place.
Cranking the packing nut down hard. The handle gets stiff, the packing wears out twice as fast, and the leak returns by July. Eighth-turn increments, test between each.
Changing the washer but ignoring the seat. If a new washer drips within weeks, the brass valve seat it presses against is probably nicked or scored, chewing up washers one after another. Run a fingertip over it; a rough seat means replacing the faucet (or the seat, on models where it unscrews).
Locate the water first and the repair picks itself: spout drip, new washer; handle leak, packing nut; water in the wall, new sillcock. Parts for the first two cost less than a pizza. And when fall comes, take the hose off — most of these repairs trace back to one hose left connected through one cold snap.
Two usual suspects. A worn packing lets water escape around the stem only under pressure, so the handle area gets wet while the faucet runs. Or a frost-proof sillcock has a split tube: its valve sits inside the wall, so nothing leaks when off, but water sprays from the split into the wall cavity while the faucet is open.
Replacing a standard hose bib typically lands in the $150 to $350 range, depending on access — a faucet threaded into an open basement is quick, while one buried behind finished walls takes longer. A plain washer swap done by a plumber often costs more in the service call than the part, which is why it's a favorite DIY.
A spout drip is wasting water but not hurting the house; fix it when convenient. A leak around the handle is similar. A split sillcock leaking into the wall is the exception — that one does quiet structural and mold damage, and it should stay shut off until it's fixed.
That cap covers an anti-siphon vacuum breaker, which keeps hose water from being sucked back into your drinking water. A brief spit when you close the faucet is normal. Continuous spraying means the rubber insert inside is worn; on many faucets it unscrews and swaps in minutes.