If you're in the market for a used car, you may want to double-down on your research. A new report from Carfax reveals an alarming 500,000 flooded vehicles are back in use, either on the road or up for sale. That's 150,000 more flooded cars, a 47% increase, than reported in 2017 when hurricanes Harvey and Irma devastated the Gulf Coast and Southeast. With Hurricanes Florence and Michael, experts at Carfax warn that even more flooded vehicles are likely to make it onto the market for resale, or back onto the road. Study analysts estimate that roughly 100,000 flood-damaged cars will be added this year. Related: Auto damage after a hurricane: comp or collision? Buying a used, flood-damaged car poses a number of health, safety, and financial risks to unsuspecting car shoppers. Water can compromise the mechanical, electrical and safety systems of a vehicle that can destroy the vehicle and create a potentially deadly scenario. Hazardous mold and bacteria could also develop in the soft parts of the car. Then there's the matter of money, where unsuspecting buyers often pay thousands more than a flooded car is worth.

The most at-risk locations

In their analysis, Carfax researchers identified the most at-risk locations for buying a flood-damaged used vehicle. The top five metropolitan areas with the most previously flooded cars back in use are Houston, New York City, Miami, Philadelphia and Dallas. In the slideshow above, find the top 10 states with the most reported flooded cars, and their percentage increase from 2017 to 2018. Related: What is a water-logged car worth?