Is Lightning Dangerous When Swimming in the Rain?

A thunder and lightning show may sound exciting––unless you’re in the water, and that’s a different story. Unfortunately, water and lightning just don’t mix. Those who have dropped their phone in any kind of water know that it almost always stops working; that’s because the water reacts with the electricity. The same idea applies with lightning. But why does this reaction happen?

The science behind lightning striking water

Scientifically speaking, water has electrolytes, which are balanced ions that are also great electricity conductors. Therefore, only pure water without minerals (distilled) will not conduct electricity; any other kind of water will. This is why swimming during a thunderstorm in any body of water, including pools, is dangerous.

Perhaps you’ve been to the pool at a time where the lifeguard blew three short whistle blasts to immediately clear the pool when thunder hit and wondered why they did this. Even with no lightning in clear sight, it’s best to err on the side of safety. Thunder is actually the sound that a nearby lightning strike causes––meaning that the lightning might not be next to you, but it’s definitely somewhere else,according to the National Weather Service.

How to calculate lightning distance

With that in mind, the NWS provides a formula that can help you calculate how far away the lightning actually is if you see a strike.

• It takes about 5 seconds for thunder to travel a mile.
• Count the number of seconds between the flash of lightning and sound of thunder, then divide by five; this is how far away the lightning is in miles.
• For easy conversion, here are some markers: 15 seconds = 3 miles, 5 seconds = 1 mile, 0 seconds = very close.

Swimming Pool Lightning Rules & Storm safety measures

Aside from the NWS, the National Lightning Institute also provides recommendations for storm safety. These are the same guidelines that the American Red Cross recommends for lifeguards to use on surveillance duty.

• Suspend all pool activities until 30 minutes after the last sound of thunder was heard. The cycle repeats after each thunder bang. So, if 20 minutes elapsed and another bang occurred, you should wait another 30 minutes before going back in the pool.
• Designate someone as the “weather safety” lookout. At commercial pools, this is often the Facility Supervisor, Aquatics Manager, or a Head Lifeguard. They will confirm whether or not there was actual thunder/lightning.
• Use a “weather radio,” a weather app, or TV program to obtain information about nearby storms.

Aside from these general precautions, you can also purchase a lightning monitor or use a lightning map to see how close the storm is. With advanced technology like this, some people may still decide to stay in the pool until the lightning is “close-by.” However, swimming pools are a bit different than other types of water due to all the hardware that comes with them: water pipes, gas lines, electrical lines, and more. Due to this, both the water and these components can conduct a very dangerous electrical shock from lightning in a pool.

Find safety indoors if there is thunder at the pool

Clearing the pool may seem like it’s enough to avoid the storm, but government agencies, such as the Centers for Disease Control and Prevention, still recommend that people remain indoors during a lightning storm. The organization also developed an extension of the NLI’s 30-minute rule: the 30-30 rule. Count to 30 after hearing lightning, and if you hear thunder before 30 seconds, then go indoors. Here’s a saying that everyone in the family can learn to remember safety protocols:

“When thunder roars, go indoors.”

However, if you can’t get indoors for any reason, the CDC recommends crouching low and avoiding direct contact with the ground as much as possible. In addition, everyone should stay away from concrete floors or walls. With this in mind, being safe indoors still requires the same precautions as being safe outdoors: avoiding close contact with anything that can conduct electricity, such as water and corded electronic equipment.

Pre-storm precautions

Even if it isn’t stormy outside, you can prepare for these storms by following a 10-day forecast on your weather app since most apps have a separate symbol for days with thunder. Thunderstorms are common in areas with high humidity because the humid air cools in the upper parts of the storms, which condenses into liquid water in the clouds, and then the heat energy that evaporates the water releases. This is why thunderstorms can still be common during mid-summer.

Here are some other great suggestions for keeping your pool safer during storms:

• Keep the pool cover off; the high winds could damage it or send it flying.
• Don’t drain the pool (if it’s not prime swimming season); this will help avoid any damage to the shell itself.
• Trim nearby trees and branches.
• Clear away toys and furniture.

Play it safe and do not return until it is safe to swim

Although lightning and thunder can seem far away sometimes, storms are unpredictable. Therefore, it’s always best to take extra precaution and ensure that everyone is safe. Kids often will become sad when they’re having tons of fun and are suddenly told to get out if they can’t see a lightning strike. I was once one of those kids, but once I learned why the lifeguards told me to get out of the pool, I didn’t feel as sad about leaving.

Reminding kids that you’re just trying to keep everyone safe can help them settle down, but an even better idea is to teach them about these dangers of thunder and lightning as well. If they know about the risks, then they might understand and be more cooperative about exiting the pool.

Jehn Kubiak’s bio:

Swim Instructor in Los Angeles, CA

Jehn is an aspiring aquatics manager who has lifeguarded for five years and taught swim lessons for three. Jehn has mostly taught for private swim schools, but she is also a certified American Red Cross Water Safety Instructor. Although Jehn loves teaching, she’s also a nerd about pool operations who thoroughly enjoys testing and balancing chemicals.