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A Closer Look at New York City's Tap Water Monsters

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


New York City is renowned for its great-tasting tap water, which is said to be amongst the purest in the country. However, when viewed under a microscope, the sight tends to disagree with the taste. Less than a year ago, it was reported that when looking at a microscopic droplet of this water, a NYC resident found tiny crustacean-like creatures floating around. The creatures—known as copepods—attack and eat mosquito larvae, helping to give the water its pure taste and are purportedly harmless to humans. While this may seem like a shocking discovery, Scientific American magazine had already reported on creepy crawling water dwellers in their October 10, 1846, issue.

microscopic water


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While acknowledging that all water, when seen at microscopic levels, has some form of "minute living animals," the article pointed to a specific sample taken from the Croton water reservoir (which supplies water to New York City) that contained "monsters." Although the image supplied is a handmade drawing rather than a photograph, there are a few creatures that look strikingly similar to copepods, while others look downright demonic. Unfortunately, there is no information about the origin of the image, so its accuracy is debatable. However, it was alarming enough for the magazine to issue a warning regarding water filtration:

"Nevertheless, the fact is readily and clearly established that the Croton water contains a quantity of deleterious matter, which is arrested by the filters; and, on this account, we cheerfully and heartily recommend the adoption of filters by all who use this water, from either the public or private hydrants. To this end we would call the special attention of our city readers to the improved filters noticed under the head of ‘New Inventions.’"

It turns out some of the supposedly "deleterious" matter was actually helping to keep the water pure, and continues to do so after all these years. Unfortunately, New York City did not make the list of finalists for the U.S. Conference of Mayors Tap Water Taste Competition, the winner of which will be announced this week at the United States Conference of Mayors in Baltimore. Maybe they need to add more monsters?

In 1845 Scientific American magazine made its debut on newsstands and has continued to be published ever since. Now, Nature Publishing Group and Scientific American are working to digitize all past issues of the magazine. Mary Karmelek is in charge of checking over each issue, and in the process she uncovers fascinating, captivating and humorous material buried in the yellowed pages of our past. In this blog she shares the highlights of her discoveries. Additional archival material appears every month in our 50, 100 and 150 Years Ago column.

More by Mary Karmelek