DEBBIE ELLIOTT, host:
Last weekend, for our Science Out of the Box series, we took a tour of a city intersection and we asked you to post your pictures of the manmade world to an account we set up on the Web site Flickr. We got more than 200 photos, and several came from Gail Dedrick.
In 1990, she moved from upstate New York to Manhattan. Like many people new to the Big Apple, she looked up and was surprised to see rickety, shingled water towers on the roofs of many buildings.
Ms. GAIL DEDRICK (Manhattan Resident): And they just seemed so incongruous. They kind of look like Petticoat Junction.
ELLIOTT: Like Monet with his haystacks, Dedrick started taking pictures obsessively.
Ms. DEDRICK: I started noticing how they looked different depending on the time of day and whether it was stormy or wintery, and it was Flickr that made me realize I wasn't alone, that there was a secret society of people who just love water towers.
ELLIOTT: So on behalf of Manhattan's water tower enthusiasts, we want to know, how do they work? We turn this question over to our expert on the industriosphere, Brian Hayes. He's the author of "Infrastructure: A Field Guide to the Industrial Landscape."
And just to be clear, we want the scoop on the water tanks in Manhattan, not the bulbous water towers in America's flatlands. As Dedrick puts it...
Ms. DEDRICK: If they're not wooden and they're not covered with shingles, they pretty much don't count.
ELLIOTT: Brian Hayes, what exactly are these water towers for?
Mr. BRIAN HAYES (Author): Well, any building that's more than five or six floors high, if you had enough water pressure to reach the upper floors, you'd be bursting pipes down at the basement. So for a long time, the city required that every building more than six stories high have its own tank on the top. And there's a pump somewhere in the basement that all day and all night long moves water up to the roof; then when it's needed, it trickles back down.
It's a technology that does go back at least to the 19th century. The two companies that build all these things - one's called Isaac's and the other is called Rosenwack(ph) - they're fourth generation family companies at this point. It's kind of like Gimbals' and Macy's in New York. You've got to be a loyalist to one or the other.
ELLIOTT: So do I understand you correctly that despite the changing technology all around us in our world, these old-fashioned water tanks are still the best when it comes to putting on buildings in New York City?
Mr. HAYES: Isn't it weird? I don't know whether it's really the best, but they're still building them and in fact they've become perhaps a little too fashionable. In Tribeca, you're now required to have one on the roof, even if you're not using it.
ELLIOTT: Now, some look like they have been there for a mighty long time. Are they safe to drink from?
Mr. HAYES: The people who build them claim that the water that comes out of a wood tank tastes better.
ELLIOTT: So these are not just wood on the outside but they're wood on the inside?
Mr. HAYES: It's wood all the way through.
ELLIOTT: Wood, wood, water. It's getting all slimy in there.
Mr. HAYES: Maybe it's the slime that makes it taste better.
ELLIOTT: I don't want to know that. Well, Brian Hayes, thanks again.
Mr. HAYES: Thank you. My pleasure.
ELLIOTT: You can post your own photo of the built environment on our Flickr page. Go to NPR.org to learn more.
You can also see two of Gail Dedrick's photos of water tanks, including one picture she snapped at the chiropractor while she was waiting in a paper gown.