A grease separator is a device that is inserted into a building's sanitation system to prevent grease from reaching the sewer.

Its use is important when fats are used in large quantities, such as in industrial kitchens, or when they are mineral fats (garage drains, for example, where their installation is usually mandatory) because they are very difficult to treat in water treatment plants.

They must also be installed at service stations (gas stations) or places where there may be a certain amount of hydrocarbons, before collecting rainwater.

They can be built or installed prefabricated. They basically consist of a container in which water pools, favoring the flotation of fats (which are less dense). They have the collection hole at a lower level, so they collect water below the lower level of the fats. Obviously the output level must be higher, so a device that allows it, such as a T, must be used before the output.

They require periodic emptying to prevent the accumulation of grease from falling to the level of the outlet. The time between emptying depends on the flow of grease that is poured into the drain.