As summer storms roll in and out, the water that collects has to go somewhere.

For homeowners on Long Island, where every area has a flood zone designation, this means flood risk is inevitable — even on properties that have never flooded before, or are in low-risk zones..

"Every time there's a new road or a new construction project nearby, it changes the way the water flows out," said Leslie Chapman-Henderson, president and CEO of Florida-based Federal Alliance for Safe Homes.

Prospective homebuyers and current homeowners alike can protect themselves against flooding, Chapman-Henderson said, so long as they take precautions early enough.

"Almost every time, once you have certainty that it's going to happen where you live, it's too late to do anything about it," said Chapman-Henderson, who lives in Florida.

Some preventative measures, like regrading a slope, can cost hundreds or thousands of dollars depending on the details; but others require much lower investment. 

At Home Depot, a six-pack of water-activated flood bags, which can absorb and redirect water, costs $39.98, according to the store's website. Empty Durasack sand bags, which serve the same purpose once filled with sand, cost $15.67 per 25 on the same site.

Whether you're a buyer or an owner

Homeowners should look at which way water travels when it rains, experts say.

Home inspector Rob Byrne, of Higher Elevation LLC, said he looks for improper sloping and drainage as well as issues with gutters or downspouts. If the property is back-pitched, or downspouts are aimed at the foundation, Byrne said, that means water is heading toward the house during or after a storm.

Current and prospective homeowners can also look for waterlines in spaces like garages or basements. Sometimes, the signs are straightforward.

"Any time there's a flood, it's always going to leave a water line, where that water was," Byrne said.

He also recommends looking at items that are on the floor.

"If it's a cardboard box and it's wet, or if there's furniture, and you see that the legs of the furniture are swollen," he said, "you know that there was a water event."

Experts recommend homeowners find out which flood zone a home is in using FEMA flood maps, check that gutters are clear, and have an awareness that topographical changes can influence the way water flows. If a homeowner adds shrubs or trees, Byrne said, even that can change the places water pools. 

According to Chapman, strategic landscaping can also help: certain plants whose root systems are especially absorbent can soak in some of the extra water, she said. 

And homeowners have agency over more than just their own properties. Chapman suggests calling the local municipality if area stormwater drains appear clogged.

It's flood season so check now

In May, National Oceanic and Atmospheric Administration forecasters predicted a "below-normal" Atlantic hurricane season this year. The season starts June 1 and extends to Nov. 30. But it does not take a hurricane to flood a property.

The National Weather Service issued five flash flood warnings for Long Island between Jan. 1 and Aug. 10 of this year, according to Newsday meteorologist Geoff Bansen. That number is on par with recent years: of the past five years, each year saw four or five flash flood warnings during the same time period, with the exception of 2024, which saw seven, Bansen said. 

Long Island's characteristic sandy soil allows for infiltration of rainwater into the ground, National Weather Service meteorologist Nelson Vaz said; but in the more developed areas, the ground cannot absorb the water as quickly as it accumulates. This can cause runoff and the flooding of streets and properties when there is an extreme rainfall event, he said.

The season has been "active" in terms of thunderstorm activity, Vaz said. Thunderstorm activity that results in flash flooding is common in July, August and September, when Long Island sees warm, humid air masses, he added.

Unlike coastal flooding, flash flooding can happen anywhere, Vaz said. At particular risk are low-lying areas amid the hills of the North Shore, and the more urbanized areas of western Long Island, he added.

Chapman-Henderson called flooding "one of the deadliest disasters," because of how quickly it happens. 

"Six inches can topple a grown, adult male, and then 24 inches can lift and move a truck, or an SUV," she said. "It doesn't take the rushing river to do that."

Long Island flood zones

According to FEMA, these zones have either a 1% annual chance flood hazard, a 0.2% annual chance flood hazard or a regulatory floodway. A regulatory floodway is the "channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height," according to FEMA.

Source: Federal Emergency Management Agency National Flood Hazard Layer