Residential Fats Oil and Grease (FOG)

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Fats, oils and grease (FOG) can cause major problems when disposed of down the drain, no matter whether you have a septic system or if you’re on town sewer. When FOG is dumped down the drain, it doesn’t flow as efficiently as other septic waste and forms large, thick grease balls that clog pipes. This causes other solid particles to get stuck resulting in blockages that can lead to slow drains or even backup of wastewater into the house. 

In septic systems, FOG doesn’t break down as easily as other forms of waste in your septic tank. Excessive FOG in the tank results in more untreated waste reducing the tank’s efficiency in processing waste.  Tanks with a lot of FOG should be pumped more often to maintain a high volume of waste being naturally processed and prevent any FOG from reaching the leaching field. If the FOG reaches the leaching field, it won’t seep into the soil restricting other treated waste from draining into the field. This may cause flooding and premature failure of your leaching field. 

In sewer systems, FOG can build up blocking sewer lines reducing the capacity of the system and its effectiveness. In severe cases, blockage can lead to sewage backup into homes and businesses and overflow onto roadways and properties causing contamination in local waterways. 

Fats, oils and grease, known collectively as FOG, represent the most serious enemy of our sewer lines.
  • Butter
  • Cooking Oil
  • Salad Dressing
  • Mayonnaise
  • Grease
  • Gravy
  • Sauces
  • Food/Meat Scraps
  • Lard
  • Margarine
  • Shortening
Grease in Residential Kitchen


  • Properly dispose of used cooking oil by pouring it into a sealable container and placing the sealed container in the trash. If you don’t have a container, place tin foil into a coffee cup or similar, add FOG, allow to cool and dispose.
  • Scrape food scraps into the trash, not the sink.
  • Wipe pots, pans, and dishes with dry paper towels before rinsing or washing them, then throw away the paper towels.
  • Place a catch basket or screen over the sink drain when rinsing dishware, or when peeling or trimming food, to catch small scraps that would otherwise be washed down the drain. Throw the scraps in the trash.
  • Rinse dishes and pans with cold water before putting them in the dishwasher. Hot water melts the fats, oils, and grease (FOG) off the dishes and into the sewer pipes. Later on in the sewer, the hot water cools and the FOG may clog the pipes.


  • Don’t use a garbage disposal or food grinder. Grinding food up before rinsing it down the drain does not remove FOG; it just makes the pieces smaller. Even non-greasy food scraps can plug your home’s sewer lines. So, don't put food of any kind down the drain.
  • Don’t pour cooking oil, pan drippings, bacon grease, salad dressings, or sauces down the sink or toilet, or into street gutters or storm drains.
  • Don’t use cloth towels or rags to scrape plates or clean greasy or oily dishware. When you wash them, the grease will end up in the sewer.
  • Don’t run water over dishes, pans, fryers, and griddles to wash oil and grease down the drain.
  • Don't flush any type of wipe down the commode. Even flushable wipes only break down into smaller pieces. This gives FOG something to cling to and build up more quickly.

Restaurants and other commercial kitchens are required to have grease traps or interceptors installed and have them pumped monthly to minimize the amount of FOG that enters the sewer system. Please contact us for more information about Mansfield Fat Oil and Grease Regulations.