Contaminated water, crumbling infrastructure, economic inequality, racial policing. Those are just a few of the topics that are likely to be main focus of the seventh Democratic debate in Flint, Michigan on Sunday night. (This was one of the debates the Democrats added to the calendar as part of the agreement for having a pre-New Hampshire debate.) The people of Flint, who are mostly African American as of the last Census estimate, are dealing with what may be the worst environmental disaster in this country's history, so both candidates will be fighting -— but not over each other — over who will do the most for Flint and communities just like it, ones that were the victims of an economic collapse and that are not often paid attention to.

Vermont Sen. Bernie Sanders issued a press release calling for Michigan Gov. Rick Snyder's resignation, and he has repeated that call several times. Former Secretary of State Hillary Clinton has also called for Snyder to step down, but she has been less adamant and repetitive than Sanders. Now, both candidates will have the opportunity to talk directly to Flint residents, so expect both to say that they will make sure something like this does not happen again, and expect that they will offer federal assistance if they reach the White House. There will also be talk about the EPA, something Republicans have said they would get rid of, but plays a role in helping Flint recover.

Crumbling infrastructure — both literally and figuratively — will be its own topic, but the latter does relate and is part of ongoing water crisis. The corrosive water combined with the lead pipes are what lead to the problem, so both candidates will likely go through their plans to replace the out-of-date pipe system in Flint and across the country. Do not expect specifics, such as a timeline or how they would pay for such a public works program. This is, though, a country-wide problem, and an expensive one at that. Fitch Ratings now believes the nation wide replacement cost could be greater than $275 billion, and the EPA believes the cost will be greater than $385 billion. The government agency's number does not even replace all of the faulty pipes.

Literally crumbling infrastructure will be a topic because bridges and roads across the United States are coming apart. Expect the candidates to bring this up as part of the greater topic of infrastructure and replacement as it relates to Flint. Sanders, who appears to have the support of white, working-class people, and Clinton, the frontrunner, will likely bring this up in the form of an economic revitalization plan that puts people back to work and repairs the infrastructure at the same time. Based on past statements and debate performances, Sanders will probably do this on a larger scale than Clinton. Both will talk about making sure Black Americans are able to have the same pay and economic opportunity as White Americans.

Given the demographic of the city, outside of water crisis umbrella, income inequality will likely be a major topic and talking point, especially for Sanders. Although Clinton has been able to win the South in large part due to the African American vote, Sanders leads among the young African American vote, and there is no doubt that he is going to use this issue to increase his lead and make a push for the older demographic. Expect both candidates, especially Sanders, to talk about fixing this problem.

Racial bias in law enforcement , which also includes racial disparity in the country's jails and prisons, will no doubt also be a central topic. If previous debates are any indication, Sanders will talk about the inequality in the country's justice system, and he will probably talk about changing sentencing laws as part of his response. He will also, likely, repeat his call for a U.S. Dept. of Justice investigation whenever someone dies from an officer involved shooting or while they are in custody.

Clinton will talk about these issues as well, but probably not to the depth and extent Sanders will. She will probably, though, explain how and why she is the better candidate to put these reforms into place, and that she is the candidate who can initiate real change.

Anderson Cooper will be lead moderator for the the debate, which will air on CNN at 5 p.m. PST from the Whiting Auditorium in Flint. Dana Bash and Don Lemon will also ask questions.

Michigan voters go to the polls for the Democrats and the Republicans on March 8.

Reach News Editor Max Schwartz here; follow him on Twitter here.