Kitchen grease is not a pretty sight. If you try to wash oily water down a kitchen sink there is bound to be a drain blockage. This is especially true in winter time when the oil turns into a solid grease ball very quickly. That is when you need a grease trap.
Waste water from almost any kitchen contains at least a bit of fat, oil and grease. This is also referred to as FOG. When these items enter the underground sewage system they are usually broken down by micro organisms in the septic tank. In a commercial kitchen it is a different story however. The amount of FOG is overwhelming and hardens causing a drain block. The only way to avoid paying a plumber to open the pipes is by intercepting greasy substances in time.
Intercepting devices has been around since Victorian times. In a nutshell an interceptor or trap is a device shaped like a box and installed between the kitchen sink and main sewage system. Most are made from metal or hard plastic and can be cleaned by hand. They should be cleaned regularly. Some oils and fat, especially those from poultry products, can start to smell bad very quickly. In some cases the companies fitting the traps will also do the cleaning.
Only use them on the kitchen sink outlets. That is where they are designed to work, not on the runoff from toilets or showers. Restaurant owners should install them even if the business has a septic tank.
They come in different sizes. The smaller ones can handle about four to eight gallons (15 to 30 liters) a minute and the bigger ones 25 to 50 (96 to 190 liters). Traps can be placed inside or outside a building. Inside traps have to be cleaned more often. They are usually not a big as those used outside.
An advantage of placing the interceptors outside is that they cause less disruption. Maintenance will be higher in winter though. Some local authorities have their own guidelines as to who must install these devices and how often they have to be cleaned. They often carry out inspections. That is because flooding the city waste water treatment plant with greasy water may put too much of a load on their system. It could become too much for the plant's outlets.
The problem seems to have a simple solution. We are dealing with grease that can melt. Just run very hot water down the drain line. Unfortunately, it is not that easy. Hot water will move the FOG only until it cools down. The blockage may then have moved up the line, but it is still there.
Not installing a trap can cost you much more than getting one. If a clogged drain in a public sewer line gets traced to your kitchen, you will have to pay quite a lot. A good interceptor can remove almost all of the grease.
FOG discharged in the sewer system is a big problem in some cities, contributing to up to a third of their sewer problems. You can help your city by installing a grease trap.