The purpose of fat, oil and grease traps in your water systems

The purpose of F.O.G traps is to prevent drains from becoming blocked up with emulsified fats. These traps keep the fats, oils and grease from entering the sewer lines which then harden in the pipes and become a health hazard. The traps are fitted with a series of baffles which keep the emulsified fats back so that cleaner water can enter the sewer lines. These systems are vital to install in environments like restaurants where fats and grease can accumulate quickly and cause plumbing nightmares.

Passive grease traps are plumbing fixtures that contain pools of rotting food waste. Fats, oils and grease (FOG) are lighter than water and float to the top of the tanks. Passive grease traps (above ground) are metal or plastic tanks required in food service facilities to prevent fats, oil and grease from entering the sanitary sewer or septic system. Grease interceptors are large in ground outdoor tanks that prevent FOG and food solids from entering the sanitary sewer or septic system at restaurant facilities.

Figure: A demonstration of how they work

To understand why grease traps are needed it is firstly necessary to explore what grease is. When you ask someone to describe grease answers will range from ‘a sticky, oily, slimy substance’ to ‘fat gone very hard.’ Grease is a complicated chemical structure that is formed from three basic substances: oil, thickener and additives. Grease is not only a by-product of cooking but used commercially as a lubricant and has many other uses also.


Why should you use a grease trap?

The answer to this question lies in the above explanation. As established water and oil do not mix therefore when it is washed down the sink it will clog pipes because it is thicker than water. Even if oil is poured down the sink as a hot substance (then it is like a liquid) once it cool its will re-solidify and the same problem presents.

Grease trap systems work from the outset and start trapping grease as soon as they are used. The most effective ones trap a high rate of grease per hour and per day which in turn helps the environment as the traps use little power.