Boston and New York cast-iron water main failures

A lot of the cast iron we put in a hundred years ago — and there's a lot of that pipe out there — has been doing pretty well for a hundred years. The reason is, if it had been steel it would corrode within thirty or forty years. Remember, that's the Achilles heel of steel. Cast iron has got three percent silicon and it forms this glassy silicon dioxide layer — it is glass basically on the surface — and that protects it from corrosion for a while. But after about a hundred years, depending on the quality of the water, that starts to break down too. Boston is an old city that started putting water pipes in a hundred years ago, and they have hundreds of miles of cast iron pipe water mains all through the city of Boston and towns hereabout.

Aging-infrastructure case. Tom's forensic heuristic: when consulting on a NYC water-pipe break, ask when the previous nearby break occurred — usually three to five years prior, because disturbing adjacent brittle pipe during repair seeds the next failure.

Then people realized wood didn't have a very long lifespan — maybe twenty or thirty years before it rots. So people started using cast iron. We use cast iron for water mains. One of the biggest problems in cities like Boston and New York is we've got hundred-year-old cast iron water mains, and every now and then one breaks. They're so brittle that when you work on it in this block, you know about five or ten years down the road the next block is going to have a leak. Because in New York City, when you go and dig up the road to replace the pipe that broke, you're going to disturb the pipe on either side. You don't want to dig up a long section of road in New York City — it tends to disturb traffic. And it helps me a lot — now you know, when I get a job in New York City and they say we had a water pipe burst, I say, when was the last one in that area? Usually there was one about three to five years earlier.