Misunderstanding Poop and Sewage

Well, sewage to be more precise. One of the harmful, but often unmentioned consequences of flooding is that our sewage systems, often decades old, are completely overwhelmed. This exposes people to sewage:

Flooding appears to be the worst problem left behind by Hurricane Irene, and especially in big cities, those floodwaters are likely to be full of raw sewage discharged by overwhelmed city sewer systems.

Believe it or not, this is by design. Many older cities in the Northeast, including Philadelphia, New York, and Boston, have what are called combined sewer systems, which carry both sewage and stormwater to water treatment facilities. When they fill up from heavy rains — like the more than eight inches dropped in many places across the Northeast and Mid-Atlantic by Irene — these “combined sewage overflows” are designed to dump untreated wastewater (meaning human sewage) into local waterways.

That means flooded communities have to worry about more than just rising water after Irene. The floods could bring significant health risks too. A study published last year in Environmental Health Perspectives found an 11 percent increase in pediatric emergency room visits for acute gastrointestinal illnesses after heavy rainfall events. Another study found high concentrations of human adenovirus, which can cause upper respiratory tract infections, in wastewater discharged into a Michigan River after heavy rainfalls…

In the U.S. each year, 85 billion gallons of untreated sewage and wastewater enters the nation’s lakes, streams, and coastal waters as a result of combined sewer overflows. If you filled Olympic-sized swimming pools with all that sewage and laid them out end to end, they would circle the earth 1.6 times.

That’s a lotta shit. But what I want to talk about is this Washington Post article. It’s pretty good, except for this clunker (boldface mine):

When rain runoff combines with water that’s flushed and drained in businesses and homes, the system backs up. Rather than allow water to bubble up in sinks and toilets, wastewater systems release it into the nearest body of water.

As a result, the level of fecal coliform that contains human waste far exceeds acceptable levels following rains. It is one reason the District’s health department maintains a ban on swimming in the city’s rivers and creeks.

I’m not even sure what that means. Here’s what I think it means: the fecal coliform level in D.C.’s rivers and creeks exceeds acceptable levels after it rains. It’s pretty obvious that neither the reporter nor the editor really understood this, but the Mad Biologist does. And we like helping!

A fecal coliform is a rod-shaped bacterium that uses lactose and can grow at 44˚C. In other words, E. coli (usually). There are a couple ways of testing for fecal coliforms. The gold standard is to filter a water sample (actually, it’s passed through consecutively smaller filters to get rid of various particle), then take all the stuff hung up on the filter and culture it. Basically, you plunk the filter onto an agar plate, and you get this:

fecalcoliform
All the blue colonies are where an E. coli cell on the filter grew into a colony. Only E. coli will turn blue.
(from here)

There are also quick colormetric tests: add your water sample, incubate, and if you have E. coli, it turns blue (that this is sorta like a pregnancy test….).

So why do we want to test for E. coli? Other than drinking other people’s poop is really gross (which seems to me to be a perfectly good reason by itself). Because when you have E. coli in the water, you’ll also have other gut microorganisms, including pathogens such as viruses–like the aforementioned adenovirus or norovirus (and, of course, E. coli can be one of those pathogens).

This is why we need science reporters: that confused sentence actually made it into print. Well, and science editors.

Anyway, that’s enough of this…shit.

This entry was posted in E. coli, Microbiology, Viruses. Bookmark the permalink.

4 Responses to Misunderstanding Poop and Sewage

  1. a) The add below the article has a picture of, um, a glass of water (a yummy thought after that diatribe)!

    b) (though I don’t think this turned out to be true):

    http://www.huffingtonpost.com/2011/08/28/tucker-barnes-irene-sewage-video_n_939351.html

  2. Er, that’s “ad below” – sorry…

  3. Narad says:

    This is why we need science reporters: that confused sentence actually made it into print. Well, and science editors.

    You innocent thing. I’ll bet dollars to donuts that that one was added by the copy desk. In fact, I’d go so far as to speculate that it started out as “the level of fecal coliform which measures human waste” and was mangled through a combination of kneejerky Elements of Stylizing and strange notions about “anthropormorphizing.” Howlers like the published version are all over actual journals that still pretend to copyediting. High volume, low wages, and the feeling that one obviously is supposed to be changing something combine quite easily.

  4. John Newcomb says:

    How much e.coli needs to be in any amount of water before we think its “polluted” and becomes sewage? After all, wild animals’ sewage goes untreated into fresh water reservoirs, lakes and streams that are often drinking water sources. If “the solution to pollution is dilution”, what is the level of dilution of sewage where it becomes safe to drink?

Comments are closed.