Can you really get struck by lightning while swimming in an indoor pool?

CHARLOTTE, NC (Theoden Janes/The Charlotte Observer) - So the other day, it happened again: I was swimming inside the Mecklenburg County Aquatic Center in uptown Charlotte, more than halfway through my workout, when all the lifeguards blew their whistles at once.

I pretended not to hear it at first, but by the time I completed another lap, one of the guards was leaning over the edge of the pool into my lane.

"Thunder," she said. "We need everyone out."

It's a pretty simple rule, and practically everyone who uses a public or community pool knows it: Any thunder or lightning – and boy, has there been a lot of both this summer – means everyone must leave the water immediately, and stay out for 30 minutes. Each additional sound of thunder or sight of lightning begins a new countdown. Once 30 thunder-/lightning-less minutes have elapsed, it's considered safe to go back in.

This rule applies to the vast majority of publicly accessible pools, both indoor and outdoor, in the Charlotte area. And I get it when it comes to outdoor swimming pools; although the Centers for Disease Control and Prevention say the odds of being struck by lightning in a given year are only around 1 in 500,000, engaging in outdoor recreational activities certainly can increase your risk.

But after my 12th (13th? 14th? I've lost count) interrupted swim this year due to a storm, I decided to try to answer a question that neither a remarkable number of phone calls nor the Internet – believe it or not – wasn't definitively able to: Can you really get struck by lightning while swimming in an indoor pool?

Before we go down this rabbit hole, I should remind you that you absolutely can be injured (or killed) by lightning while indoors. The CDC says about one-third of lightning-strike injuries occur indoors, and in fact, the very first person I talked to about this story – WBTV meteorologist Al Conklin – told me his wife's cousin was killed while talking on a landline phone in the 1960s.

There are three main ways lightning enters structures, the National Weather Service cautions on its National Oceanic and Atmospheric Administration website: a direct strike; through wires or pipes that extend outside the structure; and through the ground. "Once in a structure, lightning can travel through the electrical, phone, plumbing, and radio/television reception systems. Lightning can also travel through any metal wires or bars in concrete walls or flooring."

So it sounds plausible that it could happen to you. But according to Aquatic Safety Research Group, "There are no documented reports of fatal lightning strikes at indoor swimming pools. None! Ever!"

I searched. I searched some more. I interviewed a dozen and a half people for this story, and not one could cite a confirmed incident in which someone was electrocuted while taking a dip in an indoor pool during a thunderstorm.

In theory, though, could it happen?

Well, when I first went looking for definitive, concrete answers, I ended up more lost than those kids from "The Blair Witch Project." Duke Energy referred me to the Institute of Electrical and Electronics Engineers, which publishes the National Electrical Safety Code; the IEEE referred me to the National Fire Protection Association, which publishes the National Electrical Code; the NFPA referred me to the National Lightning Safety Institute.

OK. So I contacted the National Lightning Safety Institute to ask about the chances of getting struck by lightning in an indoor pool, and founder/CEO Richard Kithil referred me to the section about pool safety on his group's website. There's a lot to sift through, but in short – though it cites no injuries or deaths from lightning to people in indoor pools – it recommends pool activities be suspended until 30 minutes after the last time thunder is heard, for both outdoor and indoor swimming.

"It seems reasonable to NLSI," the site says, "that the potential for lightning incidents to people in indoor pools does exist."

Repeated efforts to get Kithil on the phone to discuss the recommendations were unsuccessful.

So I called an electrician – Chris Harrill of ARC Electric Company in Indian Trail. The first words out of his mouth were: "I'm not a lightning expert." But he explained that the National Electrical Code requires all pools (indoor and outdoor) to be bonded and grounded, which is complicated and would take too much space to explain fully – but essentially means electrical components (i.e. pump motors, heaters) and metallic components (i.e. ladders, rails) are rendered so that electrical potential cannot exist between them. In plain English: Pools are built in such a way that they themselves can't shock you.

Despite all this, the last words out of his mouth were: "Lightning basically will go anywhere it wants to."

Next I called a pool company – Pool By Design of Charlotte, owned by a guy named Simon Spiers. He reiterated the strict bonding and grounding requirements, also didn't claim to be a lightning expert, then signed off by saying: "I mean, personally, I think you've got more chance of being attacked by a wild boar walking down the streets of Charlotte."

Meanwhile, I reached out to Matthew Jakubowski, the facility manager for the Mecklenburg County Aquatic Center, but all he had to offer was a reminder about the minimum-30-minute-break policy and this: "Don't know anything about chances of getting struck by lightning."

Ame Guy, aquatics director for the YMCA of Greater Charlotte, said basically the same thing, adding that she sympathized with me, and their swim-focused members: "They have based their entire day around coming to our facility to swim, and all they want to do is get their workout in and increase their endorphins, and we stop that from happening. So it (the directive to exit the pool during a storm) is definitely presented with an empathetic heart, we hope, by our staff."

But she said she didn't know how serious the risk was, and that in the end the Y is basically just following the recommendations of the YMCA of the USA, the National Lightning Safety Institute, the American Red Cross and the Redwoods Group, the Morrisville-based insurance agency that covers the YMCA of Greater Charlotte.

I'd already gotten nowhere with the National Lightning Safety Institute, so I tried the Red Cross, which would only answer questions by email, and didn't address lightning as it pertained to indoor pools; instead, a spokesperson recited lightning safety tips and statistics about lightning deaths in general terms.

A representative for the Redwoods Group referred me to its lightning pool-closure policy, which basically suggests that many YMCA pool buildings are older and do not meet current codes requiring the bonding and grounding of metallic elements in the pool area. It states that "there are several documented instances of lightning striking YMCA indoor pools through glass or open windows and contacting the pool bottom, bleachers, or a lifeguard chair" (but doesn't provide links or specifics), and surmises that perhaps there have been no deaths from lightning to people in indoor pools because of the practice of clearing them during storms.

The policy underwritten by Redwoods also says Y pool buildings rarely have "lightning protection systems."

I'd actually never heard of such a thing for an indoor pool before talking to a friend's son, who is now 22 and living in New York City but spent more than half a dozen summers lifeguarding in the Charlotte area.

"I grew up swimming at Huntersville (Family Fitness & Aquatics), and they had a lightning rod I think on the top of the building," Andrew Petry told me. "I mean, it could be a hurricane outside and you'd still be swimming."

That led to a call to the Huntersville facility's aquatics director, Jessica Martin, who said that its pools' grounding and bonding was "updated" in 2008; this was prompted by a report by Aquatics International saying there was no risk to people swimming indoors during a thunderstorm. For the past decade, HFFA has only closed during storms in the event of a power outage.

"I think it is (an advantage)," she said. "Our members definitely appreciate not being disrupted for a storm that is happening outside and not affecting them indoors."

I also learned that the Queens University of Charlotte's pool – which is mostly used for competitive training but offers lap swimming to the public for a couple of hours per day – shares the HFFA's views on thunder and lightning. "We can't find anything that would indicate we should close," said Jeff Dugdale, the school's aquatics director and swim coach. "So we stay open."

Well then, after all that, what have we learned about the risk of getting struck by lightning in an indoor pool?

It's that no one seems to be able to give a definitive answer.

"I have looked and looked and looked for data that shows that a lightning strike impacted people in an indoor swimming facility, and I have yet to see anything," said Jeff Gaeckle, president of Carolina Pool Management, which oversees about 70 outdoor pools in the Charlotte area (and whose lifeguards all follow the minimum-30-minute-break policy). "But I think everybody's concerned about covering their tail; they don't want to be the one that says, 'Yeah, no problem!' – and all of a sudden something happens."