What is FOG?

Fats, oils, and grease (FOG) are by-products of food preparation and cooking. Grease is the common term used for animal fats and vegetable oils and can be found in items such as meat fats, lard, butter, margarine, cooking oil, shortening, food scraps, and baked goods.

When discharged into the sanitary sewer system, FOG can accumulate inside sewer lines, increasing the likelihood of blockages. These blockages may result in wastewater backing up into businesses, homes, or the environment, events known as sanitary sewer overflows (SSOs), which pose serious health, safety, and environmental risks.

The City of Yuma FOG Program

The Pretreatment Division’s FOG Program is designed to limit and control FOG discharges from food service establishments and to provide education to users of the wastewater system. The program’s goals are to:

• Protect public health by preventing exposure to disease-causing bacteria
• Protect private property and the City’s infrastructure from damage caused by SSOs
• Protect the environment from harm caused by SSOs
• Ensure compliance with the City of Yuma AZPDES Permit

 For additional program details, please refer to the  FOG Management Letter.

Grease Traps and Interceptors

Food service establishments that discharge wastewater containing FOG to the City of Yuma sanitary sewer system are required to install and maintain an approved grease removal device, such as a grease trap or grease interceptor.

All grease traps and interceptors must be maintained by the owner, leaseholder, or operator at their expense to ensure continuous, satisfactory, and effective operation. In addition, all applicable.  Best Management Practices for controlling FOG, as published by the City of Yuma, must be implemented.

Resources and Forms

• Training Log - Document employee instruction on FOG Best Management Practices
• Approved Service Providers - Grease trap and interceptor cleaning
• Grease Trap/Interceptor Cleaning Record
• Self-Guided Grease Device Cleaning Instructions
• How Grease Traps and Interceptors Work
• Construction Standards for Grease Interceptors

What is an Oil/Sand Separator?

Oil/sand separators (OSS), also referred to as oil/water separators, are used to remove oil, grease, and solids from vehicle wash water and floor wash water before discharge to the sanitary sewer. While effective, these devices can be costly to maintain and, if not properly managed, can contribute to surface and groundwater pollution and result in regulatory violations.

The City of Yuma OSS Program

The Pretreatment Section’s OSS Program is designed to ensure proper operation and maintenance of oil/sand separators. Program objectives include:

• Protecting public health by preventing exposure to disease-causing bacteria
• Protecting private property and the City’s infrastructure from damage caused by oil and sand
• Protecting the environment from harm caused by improper discharges and sanitary sewer overflows (SSOs).
• Ensuring compliance with the City of Yuma AZPDES Permit

Operating Your Oil/Sand Separator Effectively

To ensure your oil/sand separator functions properly:

• Eliminate contaminants: Do not rely on the OSS to handle wash water from fuel, coolant, solvent, oil, or paint spills. Clean spills immediately using dry methods.
• Wash without detergents: Avoid emulsifying cleaners, which break oil into small particles that pass through the separator and into the sewer system.
• Minimize loading: Reduce the amount of solids, oils, and wash water entering the separator. Less loading improves performance and reduces cleaning frequency.

Best Management Practices

Facilities should prevent oil and sand from entering the separator by effectively managing wash water, materials, and outdoor activities. Following the City of Yuma’s Best Management Practices Manual helps ensure ongoing regulatory compliance.

Resources and Forms

• Training Log - Document employee instruction on Oil/Sand BMPs
• Approved Service Providers - OSS cleaning and maintenance
• Oil/Sand Separator Cleaning Record
• Construction Standards for Oil/Sand Separators

FOG is a byproduct of everyday cooking. It comes from meat fats, lard, oil, shortening, butter and margarine, food scraps, baked goods, sauces, and dairy products.  FOG enters your home's plumbing system through home garbage disposals, kitchen sinks, and dishwashers.  Once inside the pipes, it coats the walls of drain lines and eventually makes its way into  It the City's wastewater system.

Why is FOG a problem?

Think of FOG as a "hardening of the arteries" in your plumbing.  Just as cholesterol build up in the bloodstream can lead to a heart attack, hardened FOG can restrict pipes and cause wastewater backups. The blockages can result in sewage overflows inside homes or onto neighborhood streets.

What can residents do to prevent FOG blockages?

You can protect your plumbing and the wastewater system by following these simple steps:

• Never pour grease down sink drains or into toilets.
• Scrape grease and food scraps into a container or the trash before washing dishes
• Collect hot grease in an aluminum foil-lined bowl.  Let it cool and harden, then remove foil and place in the trash.
• Wipe and scrape excess FOG from plates, pots, pans, utensils, and cooking surfaces before washing.

Small actions at home make a big difference in keeping pipes clear and preventing costly sewer overflows.