Fatberg column and household grease

In today’s column, Cecil points out that one primary issue is the amount of grease being dumped into the sewer system. Even before I was old enough to start cooking, my mother made it very clear that excess grease and oil was never to be dumped down the drain; instead, it was put into a disposable container (whatever we had handy) which was then thrown out in the trash.

When I moved into my own house, one of the first plumbing issues I experienced was a 2" kitchen drainpipe that was clogged almost completely by grease.

So my question is: is it not common knowledge that dumping grease into your drain is a very bad idea?

Maybe wanna fix the coding on that article’s title …

Probably not as much anymore. With garbage disposals and city sewers, you can dump a lot of stuff down the drain without thinking much about it. Back a long time ago, pipes might not have been as good so blockages were more common. They may have been in the habit of thinking about what would and wouldn’t be a problem. Also, they may have been on septic systems, which are more sensitive to what gets poured down the drain.

In addition, grease down the drain often ends up as someone else’s problem. Yes, it can clog your pipes, but that may take a very long time to happen. Most people couldn’t care less that the wastewater facility has to deal with a fatberg because of the grease they pour down the drain.

A fair point. We didn’t have our sewer system installed until I was around 13-14 years old. Before then, we had our own septic tank.

I buy cooking oil by the pint and still usually pitch half of it when it goes rancid … just checked my current bottle’s “best when used by” date and it’s Jan. 14th, 2014 … compared to health care insurance costs, keeping the sewers clean is the least of our problems …

This may be urban legend, but I’ve heard it said that if we use old oil from fast food joints in our diesel rigs, the exhaust smells like french fries … see where I’m going with this … maybe turning these fatbergs into biodiesel ain’t such a good idea …

Honestly, I’d rather smell french fries than diesel exhaust.

FOG is a concern for a lot of municipalities; it certainly is where I live, where I see occasional public service announcements about not throwing your grease down the sink. But then again, my local watershed is under federal review and fines because there are all too frequent sewer spills and the like.

As Cecil points out, while the big problem is commercial concerns that don’t handle this material appropriately, home users can no doubt bollix things up as well.

Here’s what my county says about it – there’s actually quite a few things they say about it, mostly it’s DON’T DO IT!


As for biodiesel with old cooking oil, I’m certainly no expert here but I guess with the lowish oil prices we’ve had over the last few years alternative fuels like biodiesel are not as attractive or useful. For a while there it was such a hot thing that the police actually staked out Waffle Houses and places like that because people would come steal the old oil (for reals!) but it’s been a long time since I heard any reports like that.

In this part of the country there’s been a big push towards all kinds of recycling but they also want to make a profit off of it in some way, which has proven difficult, so I suspect everything winds up in the same landfill anyway.

I was fortunate enough to read today’s question between meals-- and I appreciate Cecil’s restraint, since I’m sure he omitted many gross details.

I’m not bothering to search for links, but despite the previous sentence, the question recalled a truly disgusing tangent: I’m sure I’ve read credible accounts of persons “harvesting” fatbergs, e.g. a report that someone in China was discovered “recycling” cooking oil from sewers.

I’ll check back on an empty stomach, in case some well-informed commenter explains just how an enterprising amateur could extract usable cooking oil from the sewage-steeped solids.

In case anyone cares:

  1. Yes, that was my question. The first one Cecil* did a column on.

  2. The response time was remarkably short! I sent it in on 12/17/17. So not even a month and a half.

  3. If you form a band named “Fatberg Apocalypse”, I want a percentage. Gross, not net.

  4. “FtG” is the correct format of my name. When I signed up here I assumed that capitals might be a problem so I went lower case. (Some old Unix systems had problems with mixed case user names, for example.)

  • I’m assuming we’re on a first name basis now.

Used up vegetable oil from restaurants is rendered into tallow and animal fodder … when I was helping my mom run her bar, the local rendering plant would send a truck out and pay us to haul off the oil when we replaced it in our fryers … people just taking it from the alley would cost us money …

Rendering plants have been around since there’s been slaughterhouses … the fatbergs can be sold, it’s the sewerage backup they cause that is the problem …

I suggest a judge sentence restaurant owners who don’t maintain functional grease traps to public service i.e., having to go down and clear the obstructions themselves.

Back in the late 70’s - early 80’s I worked in fast foods in the Chicago suburbs and we were required by some “law” (not sure if it was state, local, or health dept) to not let our grease go down the drain. We had the big recycling tank out back for the old stuff from the fryers, and it had quite the unique aroma that I can still smell when I visit a restaurant - it’s like catnip for rats, btw.
But it was the grease trap that still haunts me. This 18" x 18" x 24" metal box attached to the sink that required regular “cleaning.” I cant remember if it was every week or every other, but it was something you did after hours, because just opening it up filled the restaurant with an AWFUL STENCH! Not to mention stiring up the goo by taking out the filter, which then had to be carried out back to the bin while holding it as far away from yourself (so as not to get any on ya!) and holding your breath (so as not to get any in ya), while your partner scooped the remnants out of the box into a bucket, which also then required breathless transport! and then reassembling the contraption. It all took less than 10 minutes to do but left an indelible imprint on you psyche, and more than one coworker lost his lunch during it, which added to the “charm!”

Anyway. . .this was a small box of goo. . .I cannot imagine the hideousness of a fatberg!?!


Decades ago there was a series of “Peanuts” comic strips in which Charlie Brown was sent off to summer camp, only he presumed it was going to be like army boot camp. He expressed his fear of being assigned to “clean the grease trap”. Evidently Schultz had some experience with that. An image search for this strip was unsuccessful but did show me enough pictures of filthy grease traps to make me want to never go near one.

I remember the evil grease trap theme in them Peanuts strips … I got into an argument with Charles Schultz once … if there’s no blood, then it NOT “high sticking” …

It doesn’t draw attention in the article, but Cecil does say that the bergs are made from a reaction of fatty acids with calcium from the concrete pipe. This sounds to (non-chemist) me like a very different substance from regular old grease, Any chemists care to enlighten me?

BTW I cook part-time in a pool hall in Toronto, and despite being run by cheapskates we have a grease trap that is regularly professionally cleaned. I can’t imagine anyone not doing that.

Link to the column:

It’s taking longer than we thought. :slight_smile:

New Orleans had a slightly different problem; 90,000 pounds of Gras beads.

Excuse me, it was ninety - THREE thousand pounds of beads.

Yes. Is this an enforcement problem?

… or does London have some kind of grandfathered regulatory problem?

Not a chemist, but this is fairly simple to answer:

Fatty acids are composed of an organic acid group on the end of a long hydrocarbon chain … this can form a salt when a chemical base is added to the acid group … typically we would use sodium hydroxide (lye) so we get the sodium salt of these fatty acids … kitchen counter chemistry and there’s plenty of web sites that give instructions on how to make soap at home (but be careful with the lye) …

Calcium also be used as the base in these acid/base pairs … it’s not best but it will happen … thus The Master’s claims that the grease is chemically combining with the calcium in the sewer walls to form bus-sized chunks of soap with rat-sized chunks of dead rats in them (or worse) …