Many of the older cities in the Chicagoland area have combined storm and sanitary sewers, meaning that the rain water drainage is collected through the same pipes as the sewage from houses. This type of system is almost never used anymore when constructing a new system, but many of the older cities still operate this way.
In these older cities with combined sewers it’s very common for houses to have a grease trap built in. Because the sewer system is combined, and because back when the system was built it couldn’t handle grease very well, grease traps were a way to prevent grease from entering the sewer system. Here’s a brief description of a grease trap.
A grease trap is a pit buried underground where water from the kitchen drain runs to. The exit pipe to the sewer is elevated a little bit from the bottom so that there’s always some water in the pit.
There’s a trap built over the sewer pipe, so that grease floating on the surface of the water is held back, but the water is able to run under the trap and out the sewer pipe to the sewer main. Any solid debris will settle to the bottom.
This way the grease is held back out of the sewer system. Note that only water from the kitchen flows into the grease trap. There’s no water from any other sink and certainly no water from any toilet coming into the grease trap. But there might be water from your gutters flowing into the grease trap. Where your gutter downspouts go underground they generally empty into the grease trap.
With this arrangement you’ll need to clean out the grease every so often. This used to be a much bigger issue back when we used a lot more grease in our cooking. Now you should just throw away your grease rather than putting down your kitchen sink drain. So how often you need to clean out the grease trap depends on a lot of factors, but it’s likely to be many years (probably a decade or more) before anything will need to be cleaned out. You can hire somebody to do this for you, or you can just lower a bucket on a rope to scoop out the grease and discard it.
In well over half of the grease traps I see now the trap has completely deteriorated, usually to the point where it’s completely gone. This isn’t a problem anymore and I don’t recommend that you do anything about it. There’s just no reason to. And some grease traps have been bypassed, so that the drainage from the kitchen goes directly to the sewer and doesn’t go into the grease trap at all.
These days the biggest issue with a grease trap is the condition of the ring and the lid. If the top concrete ring is damaged or the metal lid is broken then somebody could fall through. But as long as the ring and lid are in good condition then you have very little to worry about with a grease trap.
More Posts You May Find Interesting
Radiator Bleeding
There are two basic types of boiler/radiator systems. One type is the steam boiler, where the boiler actually boils the water in the system and that steam then flies through the pipes to the radiators,
fan coil units
Fan coil units are a very common way to heat and cool the individual apartments in high rise and other multi-unit buildings. Here’s some information on fan coil units. In some buildings heat and cooling
GeneralAire Model 800 Humidifier
The GeneralAire Model 800 humidifier is a notoriously terrible, old fashioned, and obsolete humidifier. But even terrible devices deserve their moment in the sun, so here’s a little bit of information about it. All you’ll
Stair dimensions
Here are some of the rules that govern stairs, including the riser heights and the tread depths. As usual though, there are plenty of disclaimers and things to keep in mind. These rules come from
Filter slot
In many cases you should take some care to seal up the slot where your furnace filter slides into. Sometimes there will be a cover that screws on or clips on, and sometimes there will
Dates for GFCI requirements
Electrical codes have changed substantially over the last couple of decades. New products and new technologies have come onto the market, sometimes on their own and sometimes at the insistence of the code-making authorities. But