There are lots of things you shouldn’t do in a thunderstorm: take shelter under a tree, use electronics or stand near a window. If you’ve ever heard the old advice about not showering during a thunderstorm because you could get an electric shock from the lightning, you might have rolled your eyes.
It turns out, though, that this isn’t a myth. It’s actually happened, although it’s rare.
“Any use of plumbing or water by a home’s occupants along the path of the lightning would be taking a lightning safety risk,” says Jeffrey Peters, the Severe Weather Program Coordinator for the National Weather Service (NWS) and a lightning safety expert.
But how can electricity from lightning get inside your house? And if showering is dangerous, what about washing dishes or your hands, or even going to the bathroom?
We asked some lightning experts what you should avoid. Any excuse to put off doing the dishes is fine by us!
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Can Lightning Travel Through Water?
Yes, and this is why lifeguards always call you out of the pool at the first crack of thunder.
Pure water is not a good conductor of electricity, says Randy Adkins, a meteorologist in the forecasting department at AccuWeather. “But the water we all consume isn’t pure,” he says. “It contains dissolved minerals, and it is these minerals that serve as a conductor for electricity.”
The pipes in our homes also make indoor water use dangerous in a thunderstorm.
“Metal plumbing pipes transmit electricity, and water can transmit electricity, as most people know,” says Dr. Mary Ann Cooper, professor emerita of emergency medicine at the University of Illinois and managing director of the African Centres for Lightning and Electromagnetics Network.
Plus, Adkins says, “copper and steel pipes are excellent conductors of electricity, as are most metals, due to the physics and chemistry of these materials.”
If you remember your high school science, metals contain electrically charged particles called electrons that can move about easily. “When provided with an electrical voltage, they will readily move and carry an electrical current,” Adkins says. This process, called conduction, allows the electricity of the lightning to move through the metal as well as the water, Peters says.
How Does Lightning Get Inside Your House?
“Lightning’s path from the cloud to the ground is one of least resistance: When lightning strikes a house, it can travel toward the ground through the plumbing, wiring or phone lines,” Peters says.
Even if it hits somewhere nearby, it could still make its way inside. “Lightning that strikes outside, nearby one’s home, can pose a danger with the lightning traveling by way of conduction underground through the metal pipes and water into your home,” he says.
It’s hard to say how close a lightning strike needs to be to potentially endanger someone inside a house, though. Adkins cites cases where lightning has been observed to travel 60 to 100 feet, but that’s outside.
“For someone indoors, it is rare for a lightning strike that far away to cause harm, even though it can travel through electrical wiring and plumbing lines located outside of the home,” he says. He says lightning typically enters a house after striking the roof.
Adds Cooper: “There is no simple answer to this, as it depends on the strength of the lightning strike, the moisture of the ground and many other factors.”
If it gets inside, though, lightning can travel through the plumbing and the water indoors. And if you’re in contact with that water by showering, the lightning can travel through you as well.
Should I Avoid the Shower, Sink and Toilet?
Peters and Adkins say they’d advise against using water inside during a lightning storm, including showering, taking a bath, doing dishes or even washing your hands. These activities increase your risk of getting a jolt.
“The danger posed with the lightning’s electricity — the average lightning bolt carries 30,000 amps of current — and the quick occurrence of lightning, in less than a second, suggest it’s best to avoid using water inside your home during a thunderstorm,” says Peters.
“Since wiring is another path that lightning takes to the ground in homes, ice makers and dishwashers pose a lightning safety risk due to the wiring and plumbing.”
Electrical appliances are also a risk, because your home’s electrical system could be a conduit for the lightning.
“Corded phones are the greatest danger since the receiver is so close to one’s head,” Adkins says. “A cordless phone isn’t an issue, provided you are not right next to the base station. Cell phones, when used indoors, are fine as well. Using a computer is a potential hazard unless you are using a laptop while not plugged in.”
The sink full of dishes can wait, too. The standard guideline is 30 minutes after the storm passes, Adkins says. You’re probably safe going to the bathroom, though.
“Using the toilet is of some small risk, but it isn’t as high as being in the shower or washing your hands for the simple fact that you are not actually immersed in the water,” Adkins says. “And if you are, then things are going horribly wrong!”
How Do I Protect My Home From Lightning Strikes?
A new type of plastic plumbing called PEX may be somewhat safer than copper or steel pipes in theory, Adkins says. “But I cannot imagine this would make a significant difference in terms of overall risk,” he says.
A better choice for protection? “A house that has an installed lightning protection system — think lightning rods — stands a much better chance of having a lightning strike take a safer path to ground, as opposed to traveling through a house’s wiring or plumbing,” Adkins says.
According to Peters, exact numbers of people injured while using or being near plumbing are hard to come by.
According to the Centers for Disease Control and Prevention (CDC), one-third of all lightning injuries (300 to 400 Americans struck per year) occur indoors. Your total risk each year of being struck by lightning is more than one in a million, according to the NWS.
And though only 10% of lightning strikes are fatal, survivors are often seriously injured.
“Data collected by the NWS indicate there hasn’t been any lightning fatalities directly related to indoor plumbing in the last 15 years,” Peters says. “Although it’s reportedly rare to be killed by lightning inside your home when using water, some who are injured are forced to cope with life-long health issues including neurological problems and pain syndromes.”
Adkins says the risk of serious injury or death from showering during a lightning strike is lower than the risk of falling in the shower or slipping on the bathroom floor. Still, if you’re concerned about being struck by lightning while indoors, avoid water or showering during a thunderstorm — even if it’s rare to be affected.
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