Whether it is safe to take a shower during a thunderstorm is a common question, and the direct answer is that a real risk does exist. Lightning is an immense discharge of electricity that seeks the path of least resistance to the ground. While being inside a substantial building offers protection, the electrical charge from a nearby strike can still enter the structure through conductive pathways. This charge can turn household activities like showering into a potential hazard, based on the physical properties of conductive materials found within a home.
How Lightning Enters a Home
Lightning does not need to strike a house directly to pose a threat, as the electrical current can be diverted into a structure through several pathways. Homes are connected to the outside world by a network of utility lines that act as a conduit for this electrical charge. These pathways include the main electrical service lines, cable and internet wires, and the plumbing or gas pipes that enter the building from underground.
Even when the flash occurs some distance away, the resulting electrical surge can travel along these utility connections. This can happen through ground potential rise, where the current spreads through the earth near the strike point and is picked up by buried pipes or wires. The utility infrastructure allows the charge to bypass the protective shell of the house and enter the internal systems.
Why Plumbing Poses a Specific Danger
The bathroom is hazardous during a thunderstorm because the water and the fixtures provide an effective path for electricity to reach a person. Lightning current easily travels through the metal pipes common in older homes and still present in newer construction, which often uses metal for fixtures and main service lines. Even where plastic pipes are used, the metal showerhead, faucet handles, and drains remain connected to the home’s overall conductive system.
Tap water is not pure; it contains dissolved mineral salts like calcium and magnesium, which turn it into an electrical conductor. When showering, you are in direct contact with this conductive water and are likely touching metal fixtures. This combination of conductive water and interconnected metal components is why safety organizations advise against using any plumbing during a storm.
Other Indoor Storm Hazards
The risk of electrical conduction is not limited to the bathroom, as any item connected to the home’s utility entry points can become dangerous. Corded electronic devices, such as landline phones or desktop computers plugged into an outlet, are connected directly to the electrical wiring system. Lightning current can travel through this wiring, causing a damaging power surge that can injure a person touching the device.
Another hazard involves contact with the physical structure of the building. Lying on concrete floors or leaning against concrete walls should be avoided during a storm. These structures often contain metal reinforcement bars, known as rebar, which can conduct a current that has entered the structure through the ground.
Staying near exterior windows or doors that may have metal frames also increases the risk of contact with a conductive pathway.
Minimizing Risk During a Thunderstorm
The best way to ensure safety is to disconnect from all potential conductive pathways while the storm is active. Experts recommend waiting a full 30 minutes after the last clap of thunder is heard before resuming normal activities. This “30-minute rule” accounts for the fact that lightning can strike far from the center of the storm.
It is prudent to avoid all water-based activities until the storm has passed, including washing dishes, running the washing machine, or bathing. For electronics, the safest practice is to unplug them from the wall outlets before the thunderstorm arrives. Cordless and cellular phones are safe to use because they do not rely on a physical wired connection to the outside world.