How Grease Traps Work and Why They Are Necessary

Basically, grease traps (also called grease interceptors) are devices used to extract fat, oil, and grease (FOG) from waste-water before it enters a municipal sewer system – or a septic system, in some cases.

Grease traps are mostly used in commercial food preparation establishments like restaurants and hotels, although they can also be effectively used in any other commercial or even domestic environment where there is a high concentration of FOGs in waste water, which can have a detrimental effect on the sewer or septic system into which the water flows.

Many local authorities have strict rules about the amount of FOGs permitted in municipal waste-water, and this makes the use of grease traps mandatory for many businesses.

Grease traps work by routing wastewater through a series of tanks (typically two), where it is allowed to cool and stand for a while. This causes separation of the contents with oily, greasy substances (liquid or solid) rising to the top, as they are less dense than water, and solid and particulate matter that is more dense than water sinking to the bottom.

Water is then allowed to flow out from the middle (vertical) part of the tanks, where the water is at its cleanest. This vastly reduces the amount of fats, oils, and greasy substances entering the public waste-water stream.