In old cities like San Francisco, water mains can be more than 150 years old and leaks happen every day. In fact, they happen 3.6 times per day, by our calculations. Most of those leaks are from cast iron pipes built somewhere between 70 and 85 years ago. The lifespan of those pipes are up right about now.
Repair crews are barely keeping up with the problem as it stands. Experts say it's only going to get worse, unless cities and states mount major investments into pipe infrastructure.
To show the extent of the problem, we asked major water agencies in San Francisco, San Jose and the East Bay to tell us where and when pipe leaks happen. We've mapped them here. Pay attention to the color of the points: the darker the color, the older the pipe. The darkest are over a 100 years old.
Sources: East Bay Municipal Utility District, San Francisco Public Utilities Commission, San Jose Water Company, City of San Jose. Map heavily inspired by the LA Times.
Notes: NBC Bay Area requested data from each of San Jose's three water agencies. We received full cooperation from San Jose Water Company, which serves about 80% of the city, and the City of San Jose, which serves another 10%. Great Oaks Water Company refused to provide geolocation data for its water main leaks.