Answer:
The writer claims that the city of Centerville needs a new infrastructure for its water system.
This claim is supported by the statement that "[the] pipes laid in the 1950s and 1960s contain lead, a toxic substance that is especially dangerous to children."
Explanation:
In the given passage, the author presents an argument where he points out the faulty water plant has become and that it is time for a new, upgraded, and improved infrastructure. With the passage of time, things become old and outdated, thus the need for new things.
The main claim of the writer seems to be that the water system should be changed and replaced by a much more modern structure.
One piece of evidence to support this claim is that "[the] pipes laid in the 1950s and 1960s contain lead, a toxic substance that is especially dangerous to children", thus the need to "modernize Centerville's aging water infrastructure."