FOG – Fats, Oils and Grease in Your Septic Tank

FOG is an acronym for fats, oils and grease and is a component of wastewater. It can also be the cause of septic tank problems.

FOG is present at some level in every septic system. The higher concentrations of FOG are found in the septic systems of restaurants, bakeries and custard and ice cream stands but can also be at elevated levels in a residential home.

The sources of FOG are numerous. It is shocking to discover how many different foods contain FOG. The classic sources are:

  • Dairy products: milk, cheese, ice cream, yogurt, butter, creams, etc.,
  • Meats: chicken, pork, beef, and processed meats like lunch meats, hot dogs and bratwursts.
  • Oils: Deep frying, olive vegetable and peanut oils.
  • Grease and lards.
  • Potato chips and other processed snacks.

FOG is problematic for septic systems (and municipal wastewater systems) because it clings to surfaces with uncanny tenacity. Think about how hot dish washing water has to get to liquify and remove lard or coagulated fat from a pan. As a result, FOG can cause blockages in pipes. To make matters worse,  FOG can capture and trap other debris and solids, making the obstruction significantly harder to remove.

FOG can also disrupt bacterial life. The reasons why are beyond the scope of this blog, but FOG is not easily consumed by bacteria. This fact, combined with FOG’s inability to be soluble or dissolved in water, means that it stays intact and never breaks down in the septic tank. The only way it can leave the system is to be pumped out.

FOG, therefore, accumulates over time at the surface of the septic tank and in the inlet pipes. Consequently, the effects it has on the septic tank and system, in general, only worsen. To clear pipes that have become clogged with FOG and other debris, the best choice is to “jet” the pipes. To eliminate accumulating FOG on the surface of the water in the septic tank, have the tank pumped.

In short, it is important to limit the amount of FOG that enters the septic lines and tank to reduce the incidence of septic tank problems. This can be done by limiting the amount of FOG used in food preparation (which also has health benefits) and by removing FOG from dishes, pots and pans and into a waste container before washing.

It is not hard to implement these precautionary measures. Doing so will eliminate expensive repair bills down the road.



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