Thunderstorms can pose dangers even when you are safely inside your home. Although many people know to avoid trees and open spaces during lightning, fewer realize that certain household activities may also carry risks. Showering, bathing, washing dishes, and doing laundry are generally best avoided when lightning is nearby because electrical currents can travel through plumbing systems.

If lightning strikes a building or nearby power lines, electricity may travel through pipes and water, potentially causing serious injury to anyone in contact with them. Homes with plastic plumbing are not completely protected, so the safest approach is to postpone water-related activities until the storm has passed. It is also wise to avoid using electrical appliances connected to outlets and corded telephones during a thunderstorm.

Lightning is extremely powerful and can cause injuries even without a direct strike. According to the National Weather Service, lightning can heat the surrounding air to approximately 50,000°F (27,760°C), causing it to expand rapidly and produce thunder. People can be injured by direct strikes, electrical currents traveling through the ground, or contact with objects that have been struck.

You can estimate how far away lightning is by counting the seconds between seeing a flash and hearing thunder. Divide the number of seconds by five to estimate the distance in miles. For example, five seconds suggests the lightning is roughly one mile away. However, this calculation should never be used to determine whether it is safe to remain outdoors.

During a thunderstorm, stay inside a substantial, enclosed building and keep away from windows, doors, plumbing, and plugged-in electrical equipment. Avoid contact with running water until the storm passes, and wait at least 30 minutes after the last thunder before going outside. Taking these precautions can reduce your risk of lightning-related injuries and help keep your family safe.