You're going waaayyyy beyond reason here. What is your basis for saying water mains last "100 years?" Here in my town, the water mains that break tend to be older ones; or ones in areas with shifting soil.
How old are the lines that are breaking in all of those stories? What kinds of soil are they in? Are there other factors involved, such as digging in the area, or heavy traffic over a portion of the line?
well... 21 water mains have broken in the last 5 1/2 days (which i found after only 30 minutes of googling)
are you saying that’s common?
That's the question. EPA study in 2002 about the need for water infrastructure replacement used this model for the longevity of water pipes:
It was assumed that pipes installed before 1910 last an average of 120 years.Pipe installed from 1911 to 1945 is assumed to last an average of 100 years. Pipe installed after 1945 is assumed to last an average of 75 years. In estimating when the current inventory of pipe will be replaced,the model assumes that the actual life span of the pipe will be distributed normally around its expected average life; that is, pipe expected to last 75 years will last 50 to 100 years, pipe expected to last 100 years will last from 66 to 133 years, and pipe expected to last 120 years will last 80 to 160 years.A large portion of the install base is quite old and is wearing out and needs to be replaced. The frequency of replacement is only going to accelerate.