Agents who work in coastal regions know that their markets are more than sprawling mansions and high-end properties. The reality is that many homes are moderately priced and they also are in danger of falling victim to rising sea levels.

According to CNBC, a report by Zillow has found that if sea levels were to rise 6 feet, 1.9 million homes, or $916 billion worth of U.S. residential real estate, could be lost.

Zillow chief economist Svenja Gudell noted that in the report Zillow looked at what types of homes would be flooded, absent preventative measures, based on the most recent estimates of sea-level increase by the end of the century.

“Living near the water is incredibly appealing for people around the country, but it also comes with additional considerations for buyers and homeowners. Homes in low-lying areas are also more susceptible to storm flooding and these risks could be realized on a much shorter timeline as we have seen time and time again.”

According to the report, 39 percent of homes expected to be underwater by the year 2100 are in the most valuable category. However, the overwhelming majority are in the median price level of about $220,000 or less. Gudell noted that owners of lower-priced homes likely don’t have the resources to take preventative measures against the rising tides, like putting in sea walls or making changes to foundations to withstand intermittent flooding.

“We’ve seen the enormous impact flooding can have on a city and its residents. It’s harder for us to think about it on a long-term timeline, but the real risks that come with rising sea levels should not be ignored until it’s too late to address them.”

For agents in Miami, New York, Boston, Tampa and Fort Myers, Fla., the highest volume of properties are at risk of flooding. Other markets at risk include Los Angeles, Charleston, South Carolina, New Orleans and Houston.