Top 10 U.S. Cities With the Most FOG-Related Sewer Blockages (2019–2023)

Fats, oils, and grease – collectively known as FOG – are a leading cause of sewer clogs and overflows across the United States. When poured or washed down drains, FOG congeals on pipe walls, trapping debris and forming hardened masses (often called “fatbergs”) that restrict flow. The U.S. Environmental Protection Agency estimates that nearly half of the 400,000 sewer blockages occurring annually in the country are caused by grease buildup. These FOG-induced blockages can lead to sanitary sewer overflows (SSOs), where untreated sewage spills into streets or waterways, creating health and environmental hazards.

In addition to public health risks, FOG blockages impose significant financial costs on municipalities – for example, New York City has spent $18–19 million per year on clearing greasy clogs and repairing related damage. Many city wastewater departments have launched public education campaigns (e.g., “Trash It, Don’t Flush It” in NYC) and stricter grease control programs to combat this issue.

Over the past five years, data from city and county wastewater reports and environmental agencies indicate that FOG remains a primary culprit in sewer blockages in numerous U.S. cities. In some cities, FOG accounts for well over half of all sewer backup incidents. The table below summarizes the top 10 U.S. cities (or counties) that have reported the highest number of FOG-related sewer blockages from 2019–2023, with available annual estimates and five-year totals.

Top 10 U.S. Cities by FOG-Related Sewer Blockages

City / Area	Estimated FOG‐Caused Blockages per Year	Approx. Total (Last 5 Years)	Sources
New York City, NY	~900–1,000	~4,000–5,000	NYC DEP, “Trash It” Campaign
Miami-Dade (Miami), FL	650+	~3,250+	Miami-Dade Public Works
Houston (Harris Co.), TX	~500	~2,500	Houston Public Works, TCEQ
Los Angeles, CA	Under 10 (recent years)	Previously 100+/yr (94% ↓)	LA Sanitation
Baltimore, MD	Dozens annually	Notable fatbergs (2017–2019)	Baltimore DPW
Detroit, MI	Dozens annually	Major fatberg in 2018	Detroit Water & Sewer
Portland, OR	High volume cleaned (not blockages)	2.4M+ lbs of grease/year	Portland Bureau of Environmental Services
Fort Wayne, IN	Frequent (est. $0.5M/year spent)	Ongoing	City Utilities Reports
Atlanta (Metro), GA	Hundreds (estimated)	No exact figure	Metro Water District, Clean Water Campaign
San Antonio, TX	130–200 SSOs/yr	Grease a major cause	SAWS

Summary of Notable Cities

• New York City, NY: NYC experiences nearly 1,000 FOG-related backups per year, accounting for 40–60% of all sewer backups. Grease is the leading cause of blockages, and the city spends nearly $19 million annually addressing the issue.

• Miami-Dade, FL: Over 650 grease clogs occur annually in this county, many causing significant environmental and health risks. The county has introduced large fines for grease violations and continues to battle high FOG blockage levels.

• Houston, TX: One in four sewer overflows in Houston are grease-related, with approximately 500 FOG blockages each year. Public awareness campaigns ramp up during the holidays when FOG issues peak.

• Los Angeles, CA: Once one of the worst cities for FOG blockages, LA has successfully reduced its grease-related SSOs by 94% through aggressive maintenance and enforcement programs.

• Baltimore, MD: The 2017 fatberg clogged 85% of a major sewer line and caused over a million gallons of sewage overflow. The city continues to monitor and address dozens of grease-related clogs annually.

• Detroit, MI: A 100-foot-long fatberg was discovered in 2018, costing over $100,000 to remove. Ongoing issues persist, though no other blockages have reached that magnitude.

• Portland, OR: The city removes millions of pounds of FOG yearly from sewer hot spots, spending $4.6 million annually to prevent future blockages.

• Fort Wayne, IN: This smaller city spends roughly $500,000 a year dealing with grease in the sewer system. It’s a clear example that fatbergs aren’t just big-city problems.

• Atlanta, GA: FOG is the number one cause of sewer clogs in the Atlanta metro area, though exact totals are spread across multiple jurisdictions.

• San Antonio, TX: Formerly had 75% of sewer backups caused by grease and wipes. After heavy investment in prevention, the city reduced SSOs by over 70%, but grease remains a key contributor to the remaining cases.

Key Takeaways

• FOG is responsible for nearly half of all sewer blockages nationwide, and some cities like NYC and Miami see even higher proportions.

• Costs are high: Cities like New York and Portland spend millions annually to prevent or repair grease damage.

• Smaller cities still suffer: Fort Wayne and Detroit highlight how smaller metros can face costly fatberg issues.

• Cities can improve: Los Angeles and San Antonio show that public education and infrastructure upgrades work.

• Fatbergs are increasing awareness: Huge clogs in Baltimore and Detroit have helped raise national attention around the dangers of pouring grease down the drain.

Sources

• NYC DEP – State of the Sewers 2023

• NYC “Trash It, Don’t Flush It” Campaign

• Miami-Dade Public Works / Grease Ordinance

• Houston Public Works / TCEQ reports

• Los Angeles Bureau of Sanitation – FOG Program Audits

• Baltimore Department of Public Works

• Detroit Water and Sewerage Department

• Portland Bureau of Environmental Services

• Fort Wayne City Utilities reports

• Metro Water District of Atlanta / Clean Water Campaign

• San Antonio Water System (SAWS)