Quick Answer:
If you hear a loud bang inside the wall when you shut off an outdoor hose, it’s usually water hammer or pipe movement, not a shattered spigot. Do a few quick checks yourself—shut the hose slowly to compare, remove the spray nozzle and retest, run at half flow then shut off, and listen at the wall penetration. If the spigot is frost‑free or the piping runs through finished walls, a plumber can often inspect and repair the problem without tearing the wall open.
Why This Happens
When flowing water stops suddenly, the moving column of water has momentum. That energy has to go somewhere and it can create a pressure spike that makes pipes bang against framing or fittings—this is commonly called water hammer. Loose pipe straps, a fast‑closing nozzle or nozzle valve, air trapped in the line, or a worn spigot stem can all make the sound louder. Similar effects happen in irrigation and sprinkler systems; see Hammering noise after irrigation shuts off and Pipes bang when sprinkler valve closes for related situations.
Step-by-Step What to Do
1. Compare a slow shut and a quick shut
- With the hose connected and water running, close the hose valve slowly and note the sound. Then open and close it quickly. If the quick shut makes a loud bang but the slow shut is quiet or softer, the problem is likely a pressure surge from stopping flow too fast.
2. Remove the spray nozzle and retest
- Unscrew any nozzle or shut‑off attachment and run the hose wide open. Close the hose valve as you did before. If the bang disappears or changes, the nozzle or its shutoff mechanism is the likely cause.
3. Run at half flow, then shut off
- Set the spigot to a reduced flow (about half). Shut it off and listen. If lower flows reduce or eliminate the bang, the pressure spike is related to how fast the line is being stopped; that points away from a broken spigot body and toward momentum/valve action or loose supports.
4. Listen at the wall penetration
- Put your ear close to where the supply pipe enters the house or the spigot’s wall flange. Try to identify whether the noise is at the spigot, inside the wall, or farther down the run. Localizing the sound helps decide whether a simple strap or an internal repair is needed.
5. Check for leaks and visible movement
- After testing, inspect the spigot stem and wall area for any drips or water stains. If the spigot leaks at the stem, stop testing and have a plumber repair it rather than trying to force it tighter.
What Not to Do
- Don’t reef on the handle trying to silence the bang or keep turning the handle after it feels closed—this can damage the valve or strip threads.
- Don’t overtighten the packing nut or stem if you see a small leak; overtightening can damage the stem and make repairs worse. If the spigot starts leaking at the stem after testing, have a plumber rebuild or replace it rather than forcing it.
- Don’t hit pipes, wall surfaces, or the spigot trying to stop the noise. That can cause cosmetic or structural damage and won’t fix the underlying pressure issue.
When to Call a Professional
- Call a plumber if the banging continues after your checks, if you find a new leak, or if the noise is loud enough to shake fixtures or plaster. Persistent water hammer can fatigue fittings and joints over time.
- If the spigot is a frost‑free model or the supply pipe runs through finished walls or floors, mention that when you call—many plumbers can inspect and repair these without tearing out drywall or siding.
- Also call if you suspect a partially closed valve elsewhere in the line, pressure regulator issues, or if you find signs of a frozen or burst pipe.
Safety Notes
- Turn off water at the shutoff for that outlet or the house main if you need to work on the spigot. Drain the line before disassembling anything.
- Avoid makeshift fixes that stress fittings. Let a qualified plumber handle internal valve rebuilds or adding arrestors.
- If you smell gas or see significant structural damage or a large leak, evacuate the area and call a professional immediately.
Common Homeowner Questions
- Why was it only one loud bang? Often a single sudden stop produces one pressure spike; repeated bangs usually mean ongoing vibration or loose straps.
- Can I install a water hammer arrestor myself? Small arrestors are DIY‑friendly if you’re comfortable shutting the water off and following instructions, but mounting and sizing are important—ask a plumber if unsure.
- Will this damage my spigot or pipes? Occasional bangs usually aren’t catastrophic, but repeated water hammer stresses joints and can cause leaks over time, so address recurring noise promptly.
For more related articles, see the Pipes Banging After Fixtures Turn Off hub.