Frozen Pipes: How to Find a Hidden Leak After a Freeze

Central Indiana winters regularly drop below 20°F, and that’s when pipes in exterior walls, crawl spaces, garages and attics start to freeze. The tricky part is that a frozen pipe usually doesn’t leak while it’s frozen. The ice plugs the crack. The leak starts when things thaw, often inside a wall or under a floor where you can’t see it. Here’s how to check your home after a freeze and find a leak before it turns into mold and ruined drywall.

Why frozen pipes leak

Water expands when it freezes. As ice forms in a pipe, it pushes the water ahead of it toward the closed faucet, and pressure builds in that short section. The pipe often splits between the ice and the faucet, not at the ice itself. That’s why the break can be several feet away from the spot that was coldest.

A freeze doesn’t always cause a dramatic burst. It can also:

• Leave a hairline crack that drips slowly
• Loosen a fitting or push a PEX connection off its crimp ring
• Crack the valve body of an outside faucet inside the wall
• Damage a washing machine or ice maker line in an unheated space

Where to look after a hard freeze

Start with the places that got cold first:

• Exterior walls, especially kitchen sinks and bathrooms on an outside wall
• Crawl spaces and unheated basements
• Garages, including water heaters and laundry lines
• Outside wall faucets (hose bibs) and the pipe behind them
• Attics with plumbing, and any pipes near vents or foundation openings
• The service line where it enters the house, if it’s shallow
• Sprinkler backflow devices and lines that weren’t drained for winter

Step 1: Do a meter test

This is the fastest way to know if anything is leaking at all.

1. Turn off every faucet, the washer, dishwasher and ice maker.
2. Look at the water meter and note the reading, or watch the small leak indicator (usually a triangle or star dial).
3. Wait 30 minutes to two hours without using any water.
4. If the reading has changed or the indicator is spinning, water is escaping somewhere.

To split the problem in half, close the main shutoff in the house and check the meter again. If it still moves, the leak is outside, in the buried line between the meter and the house. If it stops, the leak is inside. See how to find an underground water leak for the outdoor side.

Step 2: Check each area for signs

Where	What to look for
Walls and ceilings	Stains, bubbling paint, soft drywall, dripping or hissing sounds
Under sinks on outside walls	Water in the cabinet, a swollen cabinet floor, a wet back wall
Crawl space or basement	Wet insulation, puddles, dripping joints, a musty smell
Outside faucets	Water running down the foundation, or into the basement, when the faucet is turned on
Floors	Warped wood, lifting laminate, damp carpet near exterior walls
Fixtures	Low pressure or no water at one faucet while others are fine

The outside faucet test: frost-free faucets are designed to shut the water off inside the house, but a hose left connected over winter traps water in the valve. When it freezes, the valve cracks inside the wall. It stays dry until the first time you use the hose in spring. Turn the faucet on for a minute, then check the wall and ceiling on the inside for water.

Step 3: If a pipe has burst

1. Close the main water shutoff right away.
2. Turn off power to any wet area at the breaker, but only if you can reach the panel from a dry spot.
3. Open the faucets to drain the lines and relieve pressure.
4. Take photos of the damage before you clean up, for your insurer.
5. Start drying. The U.S. EPA recommends drying water-damaged materials within 24–48 hours to prevent mold growth (EPA mold guidance).

A burst pipe you can see needs a plumber. A leak you can hear or measure but can’t see needs to be located first. The full checklist is in water leak emergency: what to do in the first hour.

Step 4: Pinpoint a hidden leak before opening walls

When the meter says there’s a leak but nothing is visible, guessing costs money. Every wrong hole is more drywall, tile or flooring to replace. Professional hidden water leak detection narrows it down first:

• Moisture mapping shows how far water has spread and where it’s wettest.
• Thermal imaging picks up the cool pattern of wet drywall, or the warm bloom of a hot water line, without opening the wall.
• Acoustic listening finds the sound of a pressurized supply line leak.
• Isolation and pressure tests show which line is losing water.

Once the spot is marked, the plumber opens one small area to make the repair. For insurance claims, a thermal imaging inspection with a photo report documents where the water went. See also how professional leak detection works.

How to prevent frozen pipes

The American Red Cross recommends these steps before and during cold snaps (Red Cross frozen pipe guidance):

• Disconnect garden hoses and drain outside faucets before the first freeze.
• Drain sprinkler lines as the manufacturer or installer recommends.
• Keep garage doors closed if there are water lines in the garage.
• Open kitchen and bathroom cabinet doors on exterior walls so warm air reaches the pipes.
• Let cold water drip from faucets served by exposed pipes on the coldest nights.
• Keep the thermostat the same day and night, and no lower than 55°F if you’re away.
• Insulate pipes in crawl spaces, attics and garages with pipe sleeves or heat tape rated for the job.
• Seal drafts around pipes where they pass through exterior walls and foundation vents.

Thawing a frozen pipe safely

If a faucet only trickles on a cold morning, the pipe is probably frozen but not yet broken.

• Keep the faucet open. Running water helps melt the ice, and it relieves pressure.
• Apply gentle heat with a hair dryer, a heating pad or towels soaked in hot water.
• Work from the faucet back toward the frozen section.
• Never use an open flame, propane torch or charcoal heater.
• Watch for leaks as it thaws, and have the main shutoff ready.

If you can’t find or reach the frozen section, call a plumber.

Get the leak found

After a freeze in Bargersville, Greenwood, Franklin or anywhere in Johnson County, a moving meter or a new stain means water is going somewhere it shouldn’t. Our hidden water leak detection service finds leaks inside walls, floors and crawl spaces, and our underground water leak detection covers the buried line from the meter to the house. Contact us to schedule a visit.