The question of whether it is dangerous to shower during a thunderstorm is often dismissed as an old wives’ tale. However, this concern is based on scientific principles regarding electrical conduction and how lightning interacts with modern homes. While the probability of a direct strike resulting in injury while showering is low, the danger is real because lightning seeks the quickest path to ground. Residential plumbing can inadvertently become part of that electrical circuit. Understanding the mechanisms by which a massive electrical discharge can travel through a water system is a genuine safety precaution.
Quantifying the Risk
The likelihood of any person being struck by lightning in their lifetime is approximately 1 in 15,300, according to National Weather Service (NWS) data. Despite this small overall risk, the danger does not disappear indoors; roughly one-third of all lightning-related injuries occur inside a building.
Lightning fatalities in the United States average 20 to 35 deaths annually, with far more numerous injuries. Between 10 and 20 people in the U.S. are shocked each year while using household water or appliances during a storm. These indoor incidents confirm that injury while interacting with plumbing is a documented, recurring event, typically resulting from an indirect strike where current enters the home through utility lines.
How Lightning Finds Its Way Inside
Lightning does not need to strike a house directly to pose an indoor threat; it often uses the home’s utility connections to travel toward the ground. These connections, including electrical wiring, telephone and cable lines, and metal plumbing pipes, are bonded to the earth’s grounding system. This bonding creates a low-resistance pathway that lightning current exploits.
A strike occurring hundreds of feet away can still send ground current traveling along the service lines leading into the home. When this electrical energy enters the structure, it seeks the quickest route to dissipate into the ground. Any conductive material connected to the home’s utilities becomes a potential conduit for this electrical surge.
The current can enter a building through the main service panel, a telephone box, or the water intake point. Once inside, the current travels along the metallic components of the system, searching for a discharge point. Proximity to any utility connection—not just plumbing—is hazardous during a thunderstorm.
The Role of Plumbing and Water in Conduction
The danger in a shower or bath stems from simultaneous contact with two conductive elements: water and grounded metal fixtures. Tap water supplied to homes is not pure; it contains minerals and impurities that make it an effective conductor of electricity. This water path allows the lightning current to travel from the pipe system to the person.
In older homes, plumbing systems often rely on metal pipes (copper or galvanized steel), which are excellent conductors and provide a continuous, low-resistance pathway for the current. If a strike energizes this system, the current flows easily through the pipe walls. Even in newer construction utilizing plastic pipes, such as PVC, the risk remains.
The water inside the plastic piping remains conductive, and the current can be transmitted to the metal fixtures at the point of use, such as the showerhead, faucet handles, or drain. A person standing barefoot in a shower stall essentially completes a circuit. Their body provides a path for the electrical discharge to jump from the conductive water or fixture to the grounded plumbing below, making the shower area one of the most dangerous locations during a storm.
Essential Safety Actions During a Storm
The most effective action during a thunderstorm is to avoid contact with anything that provides a pathway for lightning current. This means refraining from all activities that involve running water, including taking a shower or bath, washing dishes, or doing laundry. Wait until at least 30 minutes after the last clap of thunder before resuming any water-related tasks.
It is also advisable to avoid using electronic devices plugged into wall outlets, as electrical wiring is a common conduit for lightning current. Unplugging appliances and electronics offers physical separation from the potential surge. Corded phones should not be used, though cordless or cellular phones are safe if they are not plugged into a charger connected to a wall outlet.
Stay away from windows, doors, and concrete floors or walls, as these structures may contain metal rebar or framing that can conduct electricity. Moving to an interior room away from utility connections and exterior walls significantly reduces the chance of injury.