Fats, Oils, and Grease (FOG)


The discharge of fats, oils, and grease, also known as FOG in the wastewater industry, is a leading cause of sanitary sewer system problems.  FOG wastes are generated at food service establishments as by-products from food preparation activities and at industrial and automotive repair facilities through leaks and spillage of petroleum-based materials.  According to the Environmental Protection Agency (EPA), FOG discharged from domestic and commercial establishments is the most common cause of reported sanitary sewer system blockages.  These blockages can lead to sanitary sewer overflows (SSOs) that result in untreated wastewater flowing into homes, businesses, or the environment. 

Restaurants, institutional facilities, and other establishments that engage in food preparation generate large volumes of fats, oils, and grease and are known as FOG facilities. 


Businesses that utilize petroleum-based oils and grease are also classified as FOG facilities.  Petroleum-based contaminants can cause negative impacts to the wastewater treatment process and they can also pass through these facilities and be discharged to the environment.


The Municipal Authority of Westmoreland County (MAWC) has specific regulations in place (Article 18) that require the utilization of FOG control devices (grease interceptors or oil/water separators) to pretreat the wastewater from FOG facilities before it is discharged to the sanitary sewer system.  To ensure compliance with these regulations, MAWC administers a FOG Program that includes routine inspections of the required FOG control devices.

Homeowners can also play a role in reducing FOG in the wastewater stream by implementing a few simple practices in their own homes.  Some examples are dry wiping plates, pouring grease into a container to cool and then disposing  of it in the trash, and avoiding the use of the garbage disposal for food scraps. 

Working together, we can reduce the accumulation of grease in the sanitary sewer system and thus help prevent sewer system blockages and SSOs. Business owners will benefit by reducing the chance of sewer backups affecting their business operations.  Homeowners will benefit by avoiding the unpleasant effects of sewer backups, which cause a great deal of inconvenience and unsanitary conditions in their homes.  In addition, reduced maintenance costs for MAWC will ultimately benefit homeowners and business owners as ratepayers.


MAWC FOG Documents:

MAWC Wastewater Rules and Regulations Article 18


Additional FOG Information:

EPA FOG Fact Sheet



NRA FOG Control Best Practices



Grease Interceptor Facts and Myths