Is the Casio F91W Waterproof?

The Casio F91W is often mistaken as a fully waterproof watch, but it is actually water-resistant. Water resistance is defined by a specific rating that indicates the degree of contact the watch can handle with water. The F91W has a rating of 30 meters (3 ATM), which means it can resist splashes and brief immersions, such as washing hands or short rain showers. However, it is not suitable for swimming or diving purposes.

Certification and Usage

According to Casio, the F91W is certified for hand washing and walking in the rain. Some users even report swimming and even diving with this watch without issues; however, it is important to note that these are not within the official specifications. For those who need a better water-resistance rating, the W217H model is a viable option. It has a water resistance rating of 50 meters (5 ATM), is slightly larger, has superior backlighting, and closely resembles the F91W in appearance.

Actual User Experience

A recent user experience shows that it is possible to swim in a pool for over an hour while wearing the F91W, all while showering before and after. Despite this, it is crucial to remember that these scenarios do not align with the watch's official specifications. Excessive water exposure, even within the water resistance limits, could still cause damage to the watch over time, as the watch is not designed for prolonged exposure to liquids.

Water Resistance Standards

Water resistance is a standardized measure. The ISO 2281 standard provides a stringent set of criteria to ensure that a watch meets the water resistance designation it claims. Key aspects of this standard include:

Immersion Test: The watch is submerged in 10 cm of water for 1 hour. Force Test: The watch is submerged in 10 cm of water with a force of 5 N applied perpendicularly to the pusher buttons for 10 minutes. Temperature and Humidity Test: The watch is placed on a heated plate between 40°C and 45°C until it reaches the temperature of the plate, typically requiring 10-20 minutes, followed by a test of water droplets on the glass. Multitemperature Immersion: The watch is submerged in 10 cm of water at 40°C, 20°C, and 40°C again, with a transition between temperatures not exceeding 1 minute. Pressure Test: The watch is immersed in a pressure vessel and subjected to the rated pressure for 10 minutes or 2 bar if no additional indication is given. An overpressure test of 2 bar is also conducted to ensure no air flow exceeds 50 μg/min.

These tests ensure that the watch can handle various levels of water exposure, but it is essential to understand that water resistance does not equate to waterproofness. While the F91W can handle light water exposure, it is not intended for prolonged or deep water activities.

Conclusion

The Casio F91W is a viable watch for those who need a watch that can handle minor water exposure. However, it is crucial to follow the water resistance guidelines and avoid exposing the watch to excessive water to ensure its longevity. For those who need better water resistance, the W217H may be a better choice.