7 Factors That Determine if a Beach is Safe to Swim

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Raise your hand if you’ve ever wondered why, exactly, a beach becomes closed for swimming—or what the difference is between a mere warning and an official closing.

We rely on local authorities to report whether or not a beach is safe for swimming, but we usually don’t know exactly what the testing consists of. Here’s what’s going on behind the scenes when authorities give beaches the red card, and how you can make your own judgment calls.

Closed for Business
A beach is typically closed when levels of bacteria in the water reach a level that is deemed to be unsafe. E. coli bacteria is the most common contaminator, which usually comes from sewage overflows and contaminated runoff water.

The decision to close a beach typically accounts for the levels recorded over a pre-determined period of time (in California, for example, they take into account the previous four weeks of water testing results).

What Makes it Okay?
Most open waters are contaminated, to some degree, with bacteria and viruses. Don’t panic—these contamination levels are typically very low, and pose no real risk to swimmers.

When these contamination levels rise to unsafe levels, that’s when it’s time to steer clear of the beach. A lot of things can cause contamination levels to rise: increased man-made pollution, sewage draining, stormy weather, the temperature, and even the number of birds going for a swim.

How Safe is Unsafe?
If you venture into the waters of a beach that’s deemed unsafe to swim in, you probably won’t dissolve on the spot. In fact, you might not even get sick—but chances are high enough that most people don’t want to risk it.

If you do get sick, you could encounter any of several unpleasant symptoms and diseases, like skin infections, pinkeye, hepatitis, dysentry, or stomach disorders. That should make you think twice about wandering onto a closed beach.

“The List”
Every year, the Natural Resources Defense Council releases a report titled “Testing the Waters”, which highlights the cleanest beaches and worst offenders in the country. The 2014 report applauds the water quality for beaches in Delaware, New Jersey, and New Hampshire, while the Great Lakes region fared the worst.

Head to the State Website
Thirty states publicize beach closings and swimming advisories on a website. Some of these lists are posted on the official state website; others have a separate site dedicated solely to the cause of beach safety. Do a good search for your state, plus the terms “beach closing” and “swimming advisory”.

Check With the Health Department
If you have questions about your favorite beach, phone the local or state health department. They should be able to give you the scoop about your beach’s condition, or at least fill you in on whether it is being monitored or not.

Making the Call
If you can’t find safety information, there are a few ways to determine for yourself which beaches might be susceptible to contamination.

Beaches in polluted urban areas are at an obvious risk. You might also want to steer clear of beaches immediately after a heavy rainfall, which can flood sewage systems, causing raw sewage to trickle down straight to the beach.

Keep your eyes (and nose) open for murky-looking or foul-smelling water, which is usually not a great sign.

You can also avoid the symptoms of illnesses brought on by contaminated water by taking a shower after swimming, washing your swimming gear and towels, and drying out your ears with a towel. Don’t go for a swim if you have open wounds.