925 sterling silver is not completely waterproof. While sterling silver is relatively resistant to water and moisture, it can still be affected by prolonged exposure to water, especially in certain conditions. Here are some important points to consider:

1. Tarnishing: Sterling silver can tarnish over time when exposed to moisture, air, and certain chemicals. This can cause the silver to become dull and discolored. Water, especially if it contains chemicals or minerals, can accelerate the tarnishing process.

2. Chlorine and Saltwater: Exposure to chlorine (e.g., in swimming pools) and saltwater can be particularly harmful to sterling silver. Chlorine can cause chemical reactions that lead to discoloration and damage. Saltwater can also corrode the silver over time.

3. Waterproof Jewelry: If you have silver jewelry, it's generally a good idea to avoid wearing it in the shower, while swimming, or during activities where it might be exposed to water for extended periods.

4. Protective Measures: To protect your sterling silver jewelry, you can remove it before swimming or showering. After wearing, gently wipe it with a soft cloth to remove any moisture and store it in a dry place. You can also use anti-tarnish pouches or containers to slow down tarnishing.

In summary, while sterling silver can handle occasional exposure to water, it's best to avoid prolonged or frequent contact with water to maintain its luster and prevent tarnishing. Taking proper care of your sterling silver jewelry will help it stay beautiful and last longer.