Should I Open Water Swim After it Rains?

I’ve heard surfers say you shouldn’t go in the water after a storm. Is that true? And how long do I have to wait?


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Most coastal counties advise people to stay out of the water for 72 hours after it rains. Surfers tend to have the hardest time heeding this advisory because big storms often bring big waves, tempting them to jump in whenever the surf’s up, advisory be damned. As a swimmer, choppy water probably isn’t as enticing, but if you must go out, here’s what you’re risking.

Storm water runoff that drains into oceans and lakes often contains high levels of fecal bacteria that can cause gastrointestinal illness. The Environmental Protection Agency’s water quality standard is based on the levels of a bacteria called enterococcus found where people recreate. One study conducted by researchers at the University of California-Irvine found that after it rains, bacteria concentrations at Southern California’s beaches can exceed bathing standards by up to 500 percent. However, researchers noted, riptides often “dilute contaminated surf zone water with cleaner water from offshore,” increasing the area of contaminated water but decreasing the concentration of bacteria enough to meet bathing standards.

Another study recently published by researchers at the same university found that the risk of getting a gastrointestinal illness from surfing after a storm was almost one-third higher than when surfing in dry conditions. A swimmer’s risk was lower, they found, likely because swimmers don’t tend to spend as much time out on the water as surfers.

But an upset stomach isn’t the worst thing that could happen from swimming in water contaminated by polluted runoff. The Lake County News-Sun reported that polluted waters in the Great Lakes can lead to other illnesses including “skin rashes, hepatitis, pinkeye and meningitis.” And if you live in Florida, wind and waves can stir up an organism that releases neurotoxins, which can cause respiratory issues in people who inhale them. (It’s the same organism responsible for red tides.)

THE BOTTOM LINE: Suck it up and head to the pool. It’s best to heed that 72-hour advisory, or risk being out of commission for 72 hours or more later on. 

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