York Water Company: Safe this year

I’m sure the rest of you who live in the region were as excited as me this past week to check the mail. Last Thursday I got my 2010 Annual Drinking Water Quality Report from the York Water Company, whose main water treatment facility is about 1 mile from the YCP campus.  Since we are discussing this in lab right now, it’s an excellent coincidence that the report showed up when it did.

The report gives a nice overview of the water sanitization process, from the main input on the Codorus Creek downstream of Lake Redman to the initial pumping station of Indian Rock Dam Road. Initially, particulate matter and organic material is removed from the water by the addition of alum, which causes that material to precipitate and settle out in large basins. The water is then passed through a series of filters, and sodium hypochlorite (bleach), ammonia, and pH adjusters are added, before the water travels to the big reservoirs at the top of the hill overlooking campus.

Water that is to come out of the tap is tested extensively for a number of things: coliforms and fecal coliforms (potentially pathogenic bacteria,) nitrates (run-off from farming,) volatile organic chemicals (byproducts of the disinfectants), and heavy metals (ground contaminants from a variety of sources.) Fortunately all of the tested parameters were well within the Environmental Protection Agency guidelines. The only item that was within a close to 2-fold level of the EPA’s action limits was dissolved nitrates, which is perhaps not surprising, given the very high levels of agriculture through the Codorus Creek watershed.

So rest assured, York County water drinkers! Everyone’s Microbiology homework is to drink at least 64 oz (1.9 liters) of tap water a day for good health and happy kidneys.

BOUNUS!  Suggest a reason why we don’t immediately shut down the water supply upon detecting coliforms in water samples.


About ycpmicro

My name is David Singleton, and I am an Associate Professor of Microbiology at York College of Pennsylvania. My main course is BIO230, a course taken by allied-health students at YCP. Views on this site are my own.

Posted on February 17, 2011, in Bonus!, Important, Lab, Meta. Bookmark the permalink. 6 Comments.

  1. There are many coliforms in our intestines already, harmlessly creating CO2 from lactose and not having any pernicious effect on our bodies. So, upon finding coliforms in the water supply I would think it would not cause any problems (they are some already in our bodies), unless they are in great excess.

    • True, our intestines harbor a large number of microorganisms in the absence of disease, but there are many organisms that cause GI diseases that might be passed via fecal transmission. Those are actually the organisms that can be the greatest cause for alarm. Let me rephrase the question: where else might coliforms in the water come from, if not from human colons? Hint: check out the Wikipedia page on E. coli.

      • Coliforms could come from animal colons. The reason why we may not get worked-up about a bunch of coliforms in the water may be because they cannot survive very long outside of a body and wouldn’t serve as a transmitable threat.

        • True, coliforms may come from animals, and not from humans. Actually, many “coliforms” can survive for a very long time outside of the colon (human or animal), and can propagate in the environment. So the presence of coliforms, may not be indicative of fecal contamination.

  2. Christian Copeland

    I don’t think we immediately shut down our water supply after detecting coliforms in water samples because a large amount of coliforms aren’t necessarily harmful to us, and for that matter, are already present in our system and passed through our fecal waste. However, there are certain types of coliforms such as rare strains of E-coli that can be extremely harmful to us and would most likely give water companies a reason to shut down that water supply.

    • Good point; many coliforms (excluding truly pathogenic strains like E. coli O157:H7, and S. enterica) are not necessarily harmful when taken in via the gastrointestinal route. We will see that even benign coliform isolates can be extremely harmful if they are able to infect a different location in the body. They also can get into the water via a number of routes in the environment. The main usefulness of coliforms is as an indicator of possible fecal contamination.

      Public health officials have a fine line to walk between maintaining a solid public infrastructure and causing mass panic unnecessarily. Because coliforms may not necessarily be indicative of fecal contamination, we use them as indicators of possible contamination, and follow up a positive result in one test with a set of confirmatory tests.

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