I stumbled across an article about 200 year old wooden water mains that were recently found during maintenance in Philly. They've since been removed from the scene to be used for educational demonstrations.
From the article:
The wooden pipes were apparently laid on "Back of Spruce, from Ninth to Tenth" between October 1811 and October 1812, according to a report from the department's archives. The department said Levine's research showed that the wooden pipe there was replaced in 1831 by a 12-inch cast-iron main.
Philadelphia began installing cast-iron pipes in 1819 and took its last wooden pipes out of service in 1858, though the pipes were not necessarily removed as they stopped being put to use.
Here's another article about them: http://www.phillywatersheds.org/resident-helps-spot%E2%80%94and-preserve%E2%80%94some-philly%E2%80%99s-oldest-water-infrastructure