"San Francisco's Aging Pipes Lead to Massive Sinkhole After Water Main Repair"
A water main break in San Francisco flooded buildings and created a massive sinkhole in the middle of an intersection. The 16-inch cast-iron water main, installed in 1949, was repaired after crews worked through the night. The area experienced intermittent water service and temporary interruptions. San Francisco's aging water pipes, with about 20% being 100 years old and made of cast iron, lead to an average of 100 to 200 water main breaks annually. Crews have completed repairs to the water main breaks and are now focusing on fixing the sinkhole.