Quick Answer:

If an outdoor spigot is leaking into a wall cavity, shut the water supply inside your home immediately, open an inspection access in the wall to find where water is spraying, and contain the wet area to limit damage. Small leaks may be temporarily contained, but you will usually need a plumber to repair the pipe or spigot and then replace wet insulation and drywall.

Why This Happens

• Freeze damage: water left in the line can freeze and crack the valve or copper/pvc behind the wall.
• Failing packing or valve: internal parts wear out and allow high-pressure spray into the wall cavity.
• Loose hose or broken connection: a hose bib connection can break off and force water into a cavity.
• Corrosion or worn pipe fittings behind siding or sheathing.

These failures often happen where the spigot passes through the sheathing or where the shutoff valve is located. If you’ve noticed the related problems **Outdoor Spigot Sprays Air Before Water** or **Outdoor Spigot Has No Water After Winter**, that history can point to freeze or valve-failure issues.

Step-by-Step What to Do

1. Shut the water off inside the house

Locate the isolation valve that controls the outdoor faucet. This is usually in a utility room, basement, or crawlspace on the same supply line. Turn it off fully. If you cannot find an isolation valve, shut off the main water supply to the house.

2. Turn off power to nearby outlets or appliances

If the wall cavity contains electrical outlets, switches, or lighting, turn off the breaker for that area before you open the wall. Water and live wiring are dangerous together.

3. Open the wall cavity for inspection

Carefully make a small inspection opening where you suspect the leak. If there’s an existing access panel remove it; otherwise cut a small square of drywall or remove a siding panel. Open only enough to see inside—larger holes can be made later by a professional if needed.

4. Look for spray marks and the source

Inside the cavity, look for active spraying, wet insulation, water stains, mineral deposits, or dark mold spots. Spray marks often show as visible tracks on framing or sheathing and will tell you which direction the leak is coming from. Follow the marks to the spigot connection or to a crack in the pipe.

5. Contain the leak

• Place a bucket under active drips and use towels to prevent runoff onto floors or finishes.
• Remove wet insulation if it is saturated—this will help drying and reduce mold risk.
• If you turned off the main and water is still present, drain the spigot and the short section of pipe by opening the spigot briefly.

6. Decide on repair vs. callout

If the leak is small and you can access a simple compression fitting or hose bib, you might be able to shut off, dry the area, and replace the spigot yourself. For any burst pipe, inaccessible leak, or if you’re unsure, stop further work and call a plumber.

What Not to Do

• Do not patch a leak inside a wall with sealant as a permanent fix — sealants can hide the problem and trap moisture, promoting mold and rot.
• Do not ignore electrical hazards—never touch wiring in wet areas with power on.
• Do not fully enclose wet insulation or drywall before it’s dried or removed; that traps moisture and leads to mold.

When to Call a Professional

• There is a steady spray or burst that you cannot stop with the inside shutoff.
• Leak is inside a load-bearing area, near electrical components, or involves structural sheathing.
• Significant wet insulation, widespread drywall saturation, or visible mold growth.
• You cannot locate the shutoff or cannot safely access the pipe.

Safety Notes

• Electricity: shut off breakers for circuits near the wet area before working in the cavity.
• Mold and air quality: exposed, wet insulation and drywall can develop mold quickly; wear a mask and gloves and limit time in the area until it’s dried or removed.
• Tools and cuts: when cutting drywall or siding, watch for hidden wiring or nails; use proper eye protection.

Common Homeowner Questions

• How quickly can water damage worsen? Within 48–72 hours mold can begin to grow in wet insulation and drywall.
• Can I just replace the spigot myself? If the shutoff works, you have clear access, and the pipe is intact, a competent DIYer can replace a spigot; otherwise call a plumber.
• Will homeowner’s insurance cover this? Coverage varies—sudden bursts are often covered, while gradual leaks may not be; check your policy and contact your insurer.