Detroit Water Department serviced Flint from 1964. Supposedly Flint wanted to build their own pipeline but it was stopped and the Detroit Water Department took over the water operations of Flint. There have to be records with the Detroit Water Department as well. 

There is a trail of corruption that has a history, but, it has no brevity to understanding Flint's water infrastructure history and putting the future on a solid path.

November 12, 2012
By Ron Fonger

...In that long-ago scheme, (click here) Flint businessman Samuel M. Catsman, a millionaire who owned real estate, coal, fuel oil and concrete companies, was indicted for fraud. He was charged with cheating the city of Flint using inside information about the planned pipeline route to buy and then sell land at a huge markup.

The scandal that peaked with the arrest of former Flint City Manager Robert A. Carter and the indictment of Catsman ended with the charges dismissed, a fat profit repaid, and the legacy of suspected corruption tied to the pipeline plans.

Within six months of the Catsman-Carter indictments, the city of Flint abandoned its pipeline project and on June 6, 1964, signed a contract to buy water from the city of Detroit for the next 30 years....

It is interesting reading, but, the only information of any importance are the players that has information regarding the pipeline system and it's construction, etc. There are other records other than the precious pieces of paper in Flint's records. Those pieces of paper, when no longer needed should be preserved in the city library along with it's story.