Yes, most indoor pools close during lightning storms. While being inside a building offers significant protection from a direct strike, lightning can travel through a building’s plumbing, wiring, and metal structural components, potentially energizing the water in an indoor pool. Most aquatic facilities follow strict closure policies that keep swimmers out of the water until the storm passes.
Why Indoor Pools Aren’t Fully Safe From Lightning
The assumption that a roof overhead eliminates lightning risk is understandable but wrong. Lightning that strikes a building doesn’t just dissipate harmlessly. It seeks a path to the ground, and that path often runs through the very systems connected to a pool: metal pipes, equipment wiring, structural steel framing, and reinforced concrete. Any of these can carry electrical current directly into pool water.
The CDC is explicit on this point: do not have any contact with water during a thunderstorm because lightning can travel through a building’s plumbing. While the risk is somewhat lower with PVC pipes than metal ones, the CDC still recommends avoiding all contact with plumbing and running water during a storm regardless of pipe material. That guidance applies to showers and sinks too, but the concern is amplified in a pool, where your entire body is submerged in water connected to the building’s systems.
There’s also the issue of ground potential differences. When lightning energizes one metallic system in a building (say, the structural steel), any other independently grounded system (like pool equipment or underwater lighting) can end up at a different electrical potential. That difference causes current to flow between the systems, or in some cases, creates electrical arcing. A swimmer in the water between those systems is in a dangerous position.
How Bonding Systems Reduce (But Don’t Eliminate) Risk
Modern pools are built with equipotential bonding, a system that electrically connects every conductive element in and around the pool: the pool shell, metal fittings, underwater lights, perimeter surfaces, electrical equipment, and even the water itself. By tying everything to the same electrical potential, bonding prevents the voltage differences that would otherwise shock a swimmer.
This bonding is required by the National Electrical Code and provides real protection under normal circumstances. But a direct lightning strike delivers an extraordinary amount of energy, far beyond what everyday bonding systems are designed to handle. Without a dedicated lightning protection system on the building itself, there is no reliable mechanism controlling where the lightning travels. It could follow structural framing, metallic piping, or equipment wiring in unpredictable ways. Even well-bonded pools can’t guarantee safety during a direct or nearby strike, which is why closure remains the standard practice.
The 30-Minute Rule
Nearly all aquatic facilities follow what’s commonly called the 30/30 rule. The pool clears at the first sound of thunder or sight of lightning, and swimmers must stay out of the water for at least 30 minutes after the last thunder or lightning flash. The National Weather Service, the American Red Cross, and most major aquatic organizations all endorse this 30-minute waiting period. If another rumble of thunder occurs 25 minutes into the wait, the clock resets.
Some organizations set even more specific distance thresholds. The YMCA of Northern Colorado, for example, mandates immediate pool closure when lightning is detected within 5 miles of an indoor pool (compared to 10 miles for outdoor pools). The tighter radius for indoor facilities reflects the reduced but still real risk.
What This Looks Like in Practice
If you’re at an indoor pool during a thunderstorm, expect lifeguards to clear the water promptly. You’ll typically be asked to move to a dry area away from the pool deck. Don’t expect to shower during the wait either, since the same plumbing risk applies. Swim lessons, lap swim sessions, and competitive meets all pause under the same rules.
For competitive swimming, meet officials generally follow the same 30-minute protocol. A storm that produces repeated thunder can delay a meet for well over an hour, since each new clap restarts the waiting period. Facilities with lightning detection systems can track storm distance in real time, which helps staff make faster, more accurate decisions about when to clear and reopen the pool.
The closures can feel frustrating, especially when you’re standing dry inside a solid building and the pool looks perfectly fine. But the physics are straightforward: lightning finds conductive paths through buildings, pools are full of water connected to those paths, and 30 minutes of waiting is a small price for avoiding a scenario where thousands of amps travel through the water you’re swimming in.