Understanding the FOG Problem

Fats, oils, and grease (FOG) are byproducts of cooking that cause repeated, expensive blockages in sewer mains worldwide. When hot liquid FOG is poured down drains, it cools, solidifies, and adheres to pipe walls. Over time, this accumulation combines with other debris—food particles, sanitary products, and mineral deposits—to form solid masses often called “fatbergs.” These obstructions restrict wastewater flow, leading to sewer backups, overflows into homes and streets, and costly emergency repairs. Reducing FOG blockages is not just a convenience issue; it protects public health, prevents environmental contamination, and lowers municipal infrastructure costs.

FOG enters sewer systems from both residential kitchens and commercial food service operations. Residential contributions, while smaller per source, add up across thousands of homes. Commercial sources—restaurants, cafeterias, fast-food outlets, bakeries—discharge much higher volumes of grease. Understanding the chemistry of FOG helps explain why it is so damaging. Animal fats and vegetable oils are triglycerides. When heated, they become liquid but revert to solid fats at cooler temperatures. Once solidified, they trap other solids, creating hard, concrete-like deposits that require hydro-jetting or mechanical cutting to remove.

The problem is global. In 2017, a 130-ton fatberg was removed from a London sewer. Similar blockages occur in cities of all sizes. The U.S. Environmental Protection Agency (EPA) estimates that FOG blockages contribute to tens of thousands of sanitary sewer overflows each year, releasing billions of gallons of untreated wastewater. Reducing FOG requires coordinated action by homeowners, businesses, and municipal authorities.

Best Practices for Homeowners

Never Pour FOG Down the Drain

The single most effective step a homeowner can take is to collect cooled fats, oils, and grease in a container and dispose of them in the household trash. Use a metal can, an empty jar, or a dedicated grease collection container. Never rinse greasy pans under hot water and assume the soap will break down the fat. Even small amounts add up over time, and liquid grease will solidify downstream.

Actionable tips:

  • After cooking, let grease cool, then scrape it into a sealable container.
  • Wipe greasy pots, pans, and plates with paper towels before washing. Place the towels in the trash.
  • Use strainers in sink drains to capture food particles, then empty the strainer into the trash.
  • Avoid using garbage disposals for greasy food scraps; the disposer only breaks solids into smaller pieces, but the grease still enters the sewer.
  • In colder climates, do not pour hot grease down the sink even if you run hot water—the water cools quickly in pipes, allowing the grease to solidify.

Laundry and Dishwasher Considerations

Grease can also enter sewers from dishwashers and washing machines if pre-rinsing is done incorrectly. Scrape large amounts of leftover food (including oily residues) into the trash before loading plates into the dishwasher. Running the dishwasher on a hot cycle with a degreasing detergent helps, but it does not eliminate all fats. For washing machines, avoid washing heavily greasy rags or mop heads at home; take them to a commercial laundry service that handles FOG-contaminated items.

Home Grease Management Systems

Some homeowners, especially those with septic systems or in areas with FOG-sensitive sewers, install small grease interceptors under the kitchen sink. These simple devices use baffles to trap grease and let water flow out. They require periodic cleaning—failure to empty them renders them useless. Check local building codes before installing; many municipalities encourage or require them in new construction.

Commercial Kitchen Requirements

Grease Traps and Interceptors

Food service establishments are the chief source of FOG in municipal sewers. Regulations typically mandate the installation of grease traps or interceptors. Grease traps are small, often located under sinks or behind cooking equipment, and serve a single fixture. Grease interceptors are larger, in-ground units that serve multiple fixtures or an entire kitchen. Both devices work by slowing down wastewater flow, allowing grease to float to the top and food solids to settle at the bottom, while relatively clear water passes to the sewer.

Key maintenance practices:

  • Clean grease traps at least weekly, or more often depending on volume. Overfilled traps cause grease to bypass into sewers.
  • Pump grease interceptors every one to three months, or as recommended by the manufacturer. Keep a log of servicing dates.
  • Do not use solvents, degreasers, or hot water to “clean” trap internals between service visits—these can emulsify the grease and send it into the pipe.
  • Inspect and clean the entire kitchen drain line, not just the trap. Grease can accumulate on pipe walls beyond the trap.
  • Train all kitchen staff on FOG disposal rules. Post signage near sinks: “No Grease Down the Drain.”

Beyond Traps: Additional Commercial Strategies

Grease traps alone are not enough. Restaurants should also implement best management practices (BMPs):

  • Dry wiping—scrape and wipe all cookware, utensils, and surfaces before washing.
  • Install floor drains with solids baskets to catch debris before it enters the interceptor.
  • Recycle used cooking oil through a licensed renderer instead of discarding it down drains.
  • Educate dishwashers about the proper use of pre-rinse sprays. Use cold water for initial rinsing to avoid melting grease.
  • Conduct regular self-audits to verify that BMPs are followed and traps are not overloaded.

Many municipalities have ordinances requiring food service establishments to maintain Water Environment Federation (WEF) guidelines for FOG control. Noncompliance can result in fines, mandatory compliance orders, or even temporary closure.

Municipal Strategies to Combat FOG Blockages

Public Education and Outreach

Local governments must lead the effort to reduce FOG blockages. A comprehensive public education campaign can change disposal habits. Use multiple channels: utility bill inserts, social media, local news, school programs, and direct mail. Simple, memorable messages like “Can the Grease” or “Put It in the Trash, Not Down the Drain” work. Provide free grease collection kits—disposable containers with lids—at city offices or hardware stores.

Ordinances and Enforcement

Municipalities should adopt and enforce FOG control ordinances. Typical requirements include:

  • Mandatory grease trap/interceptor installation for all new food service establishments.
  • Periodic inspection and reporting of trap cleaning logs.
  • Prohibition of disposing of grease into storm drains or sanitary sewers without treatment.
  • Fines or penalties for repeat offenders that contribute to blockages.
  • Pre-treatment permits for high-volume grease producers (e.g., large restaurants, cafeterias, food processors).

Inspectors can conduct random audits, respond to complaints, and use flow monitoring to detect illegal discharges. Coordination between environmental health departments, public works, and code enforcement is critical.

Sewer System Maintenance and Technologies

Even with prevention, some FOG will enter the system. Municipalities must invest in proactive maintenance.

Common maintenance approaches:

  • Hydro-jetting: High-pressure water jets break up accumulations and flush them downstream. Effective for early-stage blockages.
  • Mechanical cutting: Chain or blade cutters remove hardened grease. Used when jetting cannot penetrate.
  • Video inspection: CCTV cameras inspect pipes to identify hotspots and monitor buildup trends. Allows targeted cleaning before blockages occur.
  • Bioaugmentation: Adding specific bacteria or enzymes that digest grease. Applied through a dosing system at manholes or lift stations. Can reduce grease accumulation by 50–80% if used consistently.
  • Chemical control: Rarely used due to environmental concerns; degreasers can kill beneficial bacteria in treatment plants.

Most effective programs combine prevention (education and ordinances) with regular cleaning. A predictive maintenance schedule, based on historical blockage data and pipe condition, outperforms reactive cleanups.

Case Study: San Antonio's FOG Control Program

San Antonio Water System (SAWS) implemented a comprehensive FOG control program including mandatory grease trap inspections, a public education campaign, and a bioaugmentation pilot. Over five years, FOG-related blockages decreased by 40%, and sewer overflows dropped significantly. The program’s cost was offset by reduced emergency maintenance expenses. Similar programs in cities like Charlotte, Los Angeles, and Austin show that multi-pronged strategies are effective. SAWS’s success demonstrates that investment in FOG control pays for itself.

The Cost of Inaction

Ignoring FOG blockages leads to serious consequences:

  • Property damage: Sewage backups into basements can cost tens of thousands in cleanup and repairs. Contamination can ruin flooring, drywall, and personal belongings.
  • Public health risks: Overflows expose people and pets to pathogens. Contact with raw sewage can cause gastrointestinal illness, skin infections, and respiratory problems.
  • Environmental harm: Sewer overflows can reach streams, rivers, and lakes, killing fish and degrading water quality. Algal blooms are often fueled by nutrient-rich wastewater.
  • Infrastructure damage: Grease accumulation accelerates pipe corrosion and can collapse weak sections. Replacing a collapsed sewer main costs hundreds of thousands per block.
  • Regulatory fines: Municipalities that violate Clean Water Act permits due to FOG-related overflows face state or federal penalties.

The financial burden of reactive maintenance is immense. The EPA has published guidance encouraging utilities to implement proactive FOG management as a cost-effective alternative to emergency repairs.

Collaborative Community Solutions

Successful FOG reduction requires cooperation. Homeowners and businesses must adopt best practices; municipalities must provide education, infrastructure, and enforcement. But additional partnerships can help:

  • Waste cooking oil recycling programs: Partner with renderers to offer free collection bins at local drop-off points. Some schools use the recycled oil for biodiesel production in science classes.
  • Plumbing professional training: Work with local plumbers to promote proper trap installation and to encourage customers to adopt FOG-disposal habits.
  • Industry certification: Offer a “Grease-Free Kitchen” certification for restaurants that maintain excellent FOG practices. Publicize certified businesses to attract environmentally conscious customers.
  • Community cleanups: Organize volunteer events to map and inspect local manholes for early signs of grease buildup.

Conclusion

Reducing sewer main blockages caused by fats, oils, and grease is a shared responsibility that yields immediate and long-term benefits. Households can start today by scraping grease into the trash. Restaurants must install and maintain proper traps while training staff. Municipalities should enforce ordinances, educate the public, and deploy proactive sewer maintenance. The cost of prevention is far lower than the cost of cleanup—both financially and environmentally. By working together, communities can eliminate fatbergs, reduce sewage overflows, and protect the infrastructure that keeps our streets and homes safe. Take action now: check your own kitchen habits, support local grease recycling programs, and encourage local officials to prioritize FOG control. Clean sewers are within reach when everyone plays their part.