Guide: What Is a Sinkhole?

A small dip in the yard after heavy rain can turn into a hole without warning. Ground movement can crack foundations, snap utility lines, and flood basements. Trapped moisture can then spark black mold. This guide explains what a sinkhole is, how to spot sinkhole warning signs, and how CWF Restoration helps Chicago homeowners limit damage fast.

Sinkhole Definition

A sinkhole is a ground depression with no surface outlet. Rainwater collects in the hole and drains into the subsurface.

Sinkholes occur most commonly in karst terrain. Karst forms where groundwater dissolves rocks like limestone, gypsum, or salt. Over time, water enlarges voids underground. The surface loses support and sags or collapses.

Sinkhole vs Pothole vs Land Subsidence

• Sinkhole: Natural void or collapse below the surface that causes a depression or hole.
• Pothole: Failure of pavement materials, usually in roads or parking lots.
• Land subsidence: Gradual settling or sudden sinking from causes like aquifer drawdown, mining, or organic soil loss. A sinkhole is one cause of land subsidence, but not the only one.

Types of Sinkholes (Know the Difference)

Dissolution (Solution) Sinkholes

Acidic water slowly dissolves bedrock. Soil sags into widening joints and fractures. The result is a shallow, broad depression.

Cover-Subsidence Sinkholes

Soils above the rock gradually filter into growing voids. The surface settles over time, often creating a bowl-shaped hollow.

Cover-Collapse Sinkholes

A soil “bridge” spans an underground void until it can’t. The roof fails. The ground drops suddenly. Cover-collapse events cause the most damage and safety risk.

Natural vs Human-Accelerated Causes

Natural drivers:

• Heavy rain and groundwater fluctuations
• Long-term dissolution of soluble rock
• Erosion and soil piping

Human drivers:

• Water main breaks or leaking sewers that wash soil into voids
• Poor site drainage and uncontrolled roof runoff
• Old fill, abandoned pits, or uncompacted backfill
• Excess irrigation or redirected stormwater

These human factors can speed up a collapse that would otherwise take years.

Where Sinkholes Happen—and What It Means for Chicago

States like Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania see frequent karst-related collapses. The Chicago area has fewer classic karst sinkholes, but urban voids still form. Common local triggers include broken utilities, failing storm drains, heavy rain events, and aging infrastructure.

Chicago sinkhole impacts often show up as:

• Sudden yard depressions
• Roadway or alley failures
• Foundation cracks and basement water damage
• Broken gas, water, or sewer lines

Even without limestone beneath your home, you can face large sinkhole-like collapses from leaks and soil piping.

Early Sinkhole Warning Signs

Watch for:

• New or widening cracks in foundations, slabs, brick, drywall, or driveways
• Doors or windows that stick; uneven or sloped floors
• Tilting fences, utility poles, trees, or steps
• Soft, spongy, or sinking ground; circular surface cracks; new depressions
• Sudden muddiness in well water or unusually fast drainage after storms
• Localized pooling, hissing sounds, or unexplained spikes in your water bill (possible pipe leak)

Document changes with photos and dates, especially after major rain.

A Sinkhole Formed: What Next?

Safety First

• Keep people and pets away. Mark the area.
• Do not enter the hole. Do not pour soil or concrete into it.
• If you suspect a utility break, call the utility company. Avoid open flames.

Notify and Document

• Take photos and video from a safe distance.
• Contact your insurer early. Coverage differs for earth movement vs water damage.
• Alert local authorities if a public way, sidewalk, or utility corridor is at risk.

Call Professionals

• For structural risk and cause: a geotechnical engineer or municipal authority.
• For water intrusion, drying, and mold prevention: CWF Restoration. We remove water, control humidity, and protect wall cavities from mold growth.

How Pros Evaluate and Fix Sinkhole Impacts

Assessment

• Site walk, elevation checks, crack mapping
• Moisture readings, thermal imaging, and leak detection
• Utility inspection for breaks or cross-bores

Testing (As Needed)

• Ground-penetrating radar
• Soil borings and geotechnical analysis
• Dye tracing and CCTV of sewer lines

Stabilization (By Geotech/Civil Teams)

• Compaction grouting or low-mobility grouts to fill subsurface voids
• Engineered backfill and regrading to restore support and surface drainage
• Utility repair or reroute to stop ongoing soil loss

Property Restoration (CWF Restoration)

• Water extraction and structural drying
• Dehumidification with continuous monitoring
• Wall-cavity ventilation and targeted demolition if materials are unsalvageable
• Antimicrobial cleaning, odor control, and mold remediation where needed
• Photo documentation and insurer coordination

Prevention and Maintenance Tips

• Fix leaking plumbing and exterior hose bibs quickly.
• Extend downspouts 6–10 feet from the foundation; maintain positive grading.
• Clean gutters to prevent overflow near footings.
• Do not place ponds, large planters, or heavy water features over suspect soils without engineering input.
• After major storms, walk the property and check for new cracks, depressions, or misalignments.
• If you notice wet spots or unexplained water use, schedule a utility leak check.

FAQs

Is my issue a sinkhole or a pipe-related void?

Utility inspections and moisture mapping help confirm the cause. A leak often creates a soil cavity that mimics a sinkhole.

Will insurance cover this?

Policies vary widely. Some exclude earth movement but cover resulting basement water damage. File early and document both structural and water impacts.

Can I just fill the hole myself?

No. Filling a void without fixing the cause can trap water and trigger a larger cover-collapse later.

How fast can mold grow after a water event?

Visible growth can start in 24–48 hours in warm, humid areas. Start drying immediately.

Who should I call first?

If utilities may be compromised, call the utility provider. Next, call CWF Restoration for water, drying, and mold control. For structural risk, contact a licensed geotechnical engineer.

Why Choose CWF Restoration

We launched in 2012 with two people and a garage. Today, over 160 team members and 100+ vehicles serve the Chicago Metropolitan area. We respond fast, deliver a free inspection and estimate, and start once you give the green light.

• Rapid response, 24/7 at 1-800-597-6911
• Estimate within an hour, or we confirm your insurance coverage
• Advanced moisture detection and controlled drying
• Sanitizing and deodorizing for a clean, safe finish
• Clear communication and 100% Satisfaction Guaranteed

Clear Next Steps

• See new cracks, a fresh yard depression, or sudden basement water damage after rain?
• Call Chicago Water & Fire Restoration at 1-800-597-6911 for a free inspection and estimate.
• We remove water, stop mold, and coordinate with your insurer so your home is safe and dry again.