Folly Beach property owners can expect a 30 percent drop in their flood insurance costs because of the city's improved rating in a federal program that rewards communities for reducing their risk of flooding.

Folly and unincorporated areas of Charleston County have the highest flood preparedness rating in the state — Class 4.  The county's ranking translates to $5 million in savings or an average reduction of $275 per policy, according to the Federal Emergency Management Agency.

South Carolina has 44 counties, cities and towns participating in the federal community rating system for flood preparedness. Each has taken voluntarily steps to reduce flood risks beyond the minimum federal requirements.

The lowest insurance discount is 5 percent for eight rural areas including Port Royal and unincorporated Florence and Orangeburg counties. Hilton Head, Kiawah Island and five other affluent coastal communities have flood readiness programs that qualify residents for a 25 percent discount.

Fourteen locales including Beaufort, Hollywood, unincorporated Colleton County, North Charleston and unincorporated Horry County receive a 15 percent break, according to FEMA.

At Folly, the tab for flood insurance will drop 30 percent in high-risk zones and 10 percent in low-risk areas. The lower flood insurance rates will apply to new and renewing policies effective after May 1, 2018, said Danon Lucas, FEMA spokesman.

The FEMA flood preparedness ranking ranges from a top rating of Class 1 to a bottom ranking of Class 9. The program rewards communities that willingly implement increased flood protection, preparedness and mitigation measures.

Folly officials said the 30 percent discount affects the whole island because all of the city sits in a high-risk flood zone. The island hired a consultant to improve its rating from Class 7 to Class 4. One of the benefits of that move was the reclassification of wetlands as open space.

Charleston residents qualify for a 20 percent discount, while North Charleston sees the cost of flood insurance reduced there by 15 percent. Residents of unincorporated Greenville, Richland and Berkeley counties get a 10 percent discount.

Flood damage prevention programs are rated every three to five years. Communities that rank higher such as Folly and Charleston County are evaluated every three years. Places with lower ratings are reviewed every five years.

Meanwhile, it's too soon to say how Tropical Storm Irma and other flood events — and local governments' response to them — will affect ratings across the state.

"We have not prepared a study on South Carolina as a result of the recent flooding events in 2015, 2016 and this year," Lucas said. "So nothing definitive on trends."

Reach Prentiss Findlay at 843-937-5711.