JOHN YANG: There's a city of 150,000 people where for years residents have been periodically advised to boil the tap water.

And for a week last summer, there was no reliable water service at all.

It's not in a developing nation.

It's here in the United States.

Jackson, Mississippi.

While extreme, it's not an isolated case.

Last year, drinking water was found to be tainted in parts of New York City, Baltimore and the state of Hawaii.

Of course, Flint, Michigan is still coping with the effects of its lead contamination.

Why are so many cities having problems with drinking water?

Shannon Marquez is Dean of Global Engagement and professor of Water, Sanitation and Hygiene at Columbia University.

Shannon, I'm just going to start with that question.

Why does one of the most prosperous nations in the world have trouble delivering safe drinking water into everyone's home?

SHANNON MARQUEZ, Columbia University: I think this is a very complicated issue where we have a number of things that have come to a head all at one time.

First, we have aging infrastructure and repairs and maintenance that have really lagged because states and local governments have been overburdened and juggling these funding priorities for a number of years.

And if you think about that means that communities that have been historically underfunded or underserved are disproportionately being impacted.

That coupled with climate change and extreme weather events and flooding are increasingly impacting water systems and that aging infrastructure then also begins to impact contamination.

So, old pipes really can leach and the pole plumbing can corrode and lead contamination from these leaching pipes and becomes a health issue.

JOHN YANG: This has come to a head in a number of cities that we walked through.

But is this more widespread?

Are there other cities having the same problem, perhaps lower intensity?

SHANNON MARQUEZ: Absolutely.

Unfortunately, we are only hearing in the news when there are these extreme events when cities have boil water advisories.

But the lack of financing to rehabilitate old water system means that systems have been neglected for years.

So, increasingly we are going to hear more and more about this.

But unfortunately, I'm afraid to say there are many communities who are facing these challenges right now.

We're not hearing about all of them.

JOHN YANG: I know you work on water security in underdeveloped nations.

Does some of the things you see in these cities remind you of the things you see overseas?

SHANNON MARQUEZ: Absolutely.

Many communities who are facing these challenges where there's a water emergency, they are having to plan their day, plan their livelihood, plan their life around accessing safe water and also how to deal with wastewater.

And this really does mirror many of the concerns in low middle income countries.

JOHN YANG: Is there a simple answer to explain why Americans or why cities in America have allowed the water systems to reach this state?

SHANNON MARQUEZ: You know, there are a combination of things.

One, communities are generally uninformed about the vulnerabilities and challenges with water systems.

For example, when there's a water main break, it's usually reported in the context of a traffic disruption, not the fact that there's aging infrastructure or there are potential challenges with water quality or conveying the water as a result of that main break.

Water is not a commodity that's properly valued in our country.

People really take for granted that it's going to be readily available and safe and they do not realize what it truly costs to protect water systems and make them reliable.

And then I would say that environmental racism and what we're seeing with communities who are disproportionately impact.

It's quite evident since that the historical disinvestment in communities of color really mirrors the institutional racism and other barriers that have become existed in our country in the troubled history.

JOHN YANG: The cities we talked about.

Jackson is 80 percent black, Flint is 60 percent black.

Benton Harbor, Michigan, another city with lead contamination problems, 80 percent black.

Now, the President's been going around the country talking about his infrastructure bill.

Is that going to provide any help or is it going to be enough help?

SHANNON MARQUEZ: Unfortunately, although this is probably the most resources and finance that have been put toward and directed toward this problem in a number of years, unfortunately, that 55 billion is not going to be enough.

It literally is just a drop in the bucket because the cost of fixing America's drinking water infrastructure will be nearly $480 billion over the next 20 years.

And it's evident that the infrastructure package will not meet the full need.

It's also a complicated mix of criteria that communities must meet, and that falls with the states to really decide who is going to receive and prioritize those projects while all this is happening because it takes so long to implement change in a water project, the infrastructure is going to continue to age and the need for investment will grow.

JOHN YANG: Shannon Marquez, Columbia University.

Thank you very much.

SHANNON MARQUEZ: Thank you.