A water resistance rating is a statement about a specific laboratory test. Knowing what that test involves explains most of the gap between the rating and everyday experience.
The rating describes a controlled test
Certification involves submerging a sealed device in still, clean, fresh water at a defined depth for a defined period at room temperature.
Both digits in the rating carry meaning: the first covers solid particles such as dust, the second covers liquid, and a high liquid figure implies nothing about dust.
Nothing in the test resembles a swimming pool, the sea or a shower, which is the source of most misunderstanding.
Pressure and movement change everything
Static depth is not the same as moving water. Swimming, a jet from a tap or the impact of a wave produces pressures well above the static figure.
Seals are rated against the tested pressure, and a brief spike beyond it can push water past a gasket that would hold indefinitely at rest.
This is why manufacturers advise against pressurised water even on devices rated for submersion.
Only fresh water was tested
Salt water corrodes seals and contacts, and it leaves deposits as it dries that prevent a gasket from sealing correctly afterwards.
Soap, shampoo and detergents reduce surface tension, allowing liquid through gaps that would repel plain water.
Chlorinated pool water and hot water both degrade adhesives and gaskets over time, and heat additionally expands the air inside a sealed device.
The rating describes a new device
Seals are adhesives and gaskets that age. They are affected by heat cycling, by drops that flex the chassis and by any repair that opens the device.
Ratings are measured on new units, and no manufacturer claims the figure persists through the product's life.
This is why liquid damage is commonly excluded from warranty coverage even on devices marketed with a submersion rating, and why devices carry indicators that reveal exposure.
What to do after exposure
Rinsing with fresh water after contact with salt or soap removes residue before it dries into the seals and speakers.
Charging ports must be dry before power is applied, since current through a wet connector causes corrosion and short circuits that survive the water drying.
Air drying at room temperature is slow and safe, while heat sources risk damaging the same seals the rating depended on.
Speakers often clear themselves once dry, since the water sits in a chamber designed to drain, and forcing air into the opening can push it further in instead.