What's breaking the water mains in Washington, DC?
July 27, 2010 7:38 PM   Subscribe

Are water mains more likely to break in the middle of summer? There have been many water main breaks in the DC area lately.

I know that the US has a lot of aging infrastructure, and water mains will break from time to time as a result. On the other hand, it seems like Washington, D.C. has been hit with more than usual this summer; I count six incidents this month!

I thought that water mains broke most often from freezing in winter cold; is there a similar effect from expansion in summer heat? Or are we just witnessing the end result of municipal neglect?
posted by LightStruk to Science & Nature (10 answers total)
The City of Los Angeles has been struggling with a series of water main breaks due to water rationing days, creating uneven pressures that broke the aging pipes. A dedicated search on the LA Times website under LA Department of Water and Power will give you a history of the problem.
posted by effluvia at 8:00 PM on July 27, 2010

2nding effluvia - we had this exact thing happen last summer in LA because people could only water on two days of the week, so the mains were overwhelmed on those days and busted.

Even if there's no water rationing in DC, if the summer is unusually hot I bet there's just more demand for water for lawns, pools, swamp coolers, cold showers, etc than the mains can handle.
posted by little light-giver at 8:06 PM on July 27, 2010

I remember that at least a few broke in NW / Chevy Chase this past winter. DCist probably reported on it?

And you're right, DC infrastructure is so ready for an overhaul. Especially Metro!
posted by charmcityblues at 8:31 PM on July 27, 2010 [1 favorite]

There was a break in Chevy Chase over the winter.
posted by defcom1 at 8:52 PM on July 27, 2010

Most probably, those mains were laid around the same time, have been maintained to the same degree, and hence are failing around the same time. The heat wouldn't be a particular factor, nor particularly should changes in demand.

Various materials are used for constructing water mains, and as with other things, the cheaper options may not last as long as others - eg standard concrete pipes have a 40-80 year lifespan, while various metal, plastic, ceramic will vary, as will various types of concrete too, depending on what materials are available locally.

While we're on it, few people also recall that water mains hold water under a lot of pressure. That water pressure you get from the tap? Multiply that by hundreds of taps in your immediate neighbourhood. Sewers by contrast appear largely empty most of the time (a small flow along the bottom of the pipe as you'll often see in TV and movies), because you need lots of capacity to deal with inflow when it rains heavily, and you don't want your sewers overflowing at this time because of all the extra water that comes in.
posted by jjderooy at 8:55 PM on July 27, 2010

Best answer: Water mains break all the time. Up in the Maryland suburbs, WSSC had 2,129 water main breaks and leaks last year. DC is fixing two other breaks as we speak. And as a random non-US example, Sydney Water had 7,254 water main breaks and leaks in 2009. Certainly aging infrastructure has a lot to do with it (as the WSSC FAQ makes clear), but it seems like the media only report on the more dramatic breaks: sinkholes, traffic tie-ups, 100-foot geysers, that sort of thing. So I suspect that this is somewhat due to chance; we happen to have had several dramatic newsworthy breaks, but all of the run-of-the-mill breaks never make it into the news.
posted by av123 at 9:46 PM on July 27, 2010

Best answer: DC water mains are really old. Under Pennsylvania Avenue and up to the Capitol, there's an unlined iron main that dates back before the Civil War. More than 180 miles of water mains in the District date back more than a century. Then there are the eels that used to swim through the pipes. Here.
posted by exphysicist345 at 10:29 PM on July 27, 2010 [2 favorites]

High heat causes pavement to expand. These stresses can cause the pipes below to stress beyond its ability.
posted by gjc at 4:09 AM on July 28, 2010

IANA plumber, but I work in liability insurance for municipalities and deal with a lot of claims resulting from water main breaks. I haven't noticed breaks occuring in clumps based on weather, and while it's not terribly cold where I live, the pipes are under pressure and water is moving within them so it shouldn't generally freeze in winter.

What does cause water main breaks in summer? The thing that immediately comes to mind is increased construction and public works projects in the spring and summer months. Sometimes a backhoe will be the direct cause of a break, sometimes simply the vibrations from construction or roadwork will cause a break, etc.

More generally? Ground movements over time, soil acidity, tree roots, even a main having been laid over a rock or something eventually causing a break. People doing renos or yardwork without checking first where they're digging. You'd be surprised how often it happens. Keeps me employed, anyway!

Also, just to echo the ideas expressed above, water mains have a lifespan like anything else, and they're often installed all at once when a development is first being built--or even when mains are being replaced. Even if they come to the end of their natural 'lives' without incident, you can expect more than one main to break around the same time even under the best circumstances if they're the same age. Nothing lasts forever.

Hope that helps a bit.
posted by Kirk Grim at 8:20 AM on July 28, 2010

Response by poster: All of these answers are helpful. Thanks everyone!
posted by LightStruk at 10:38 AM on July 28, 2010

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