Water Ratings Technology Explained

Water ratings technology refers to the systems used to measure and communicate how water-resistant or waterproof a product is, typically expressed as an ingress protection (IP) code or an atmospheric pressure rating in millimeters or meters. You enter a product’s rating or test conditions, and the calculator converts it into a practical depth or pressure value, helping you compare devices, watches, and outdoor gear. This article explains the standards, how ratings are tested, and what they mean for real-world use.

What Do Water Ratings Mean?

Water ratings are standardized ways to tell consumers how much water exposure a product can handle. The two most common systems are the IP (Ingress Protection) code and the atmospheric pressure rating (often stated in meters or ATM). The IP code, defined by international standard IEC 60529, uses two digits: the first for solid particle protection (0-6) and the second for liquid ingress (0-8). For example, IP68 means dust-tight and protected against continuous immersion beyond 1 meter (the exact depth is specified by the manufacturer). The ATM rating, common on watches, is based on static pressure: 1 ATM equals 10 meters of water column, but that does not mean you can dive to 10 meters—movement and temperature change the pressure dynamics.

How Water Resistance Is Tested

Manufacturers test water resistance in controlled laboratory conditions, usually with a pressure chamber that applies static water pressure. For IP ratings, the test for IPX7 involves submerging the device in 1 meter of water for 30 minutes. IPX8 requires continuous immersion at a depth specified by the manufacturer (often 1.5 meters for 30 minutes). For watches, the ISO 22810 standard defines water resistance for daily use, while ISO 6425 covers divers’ watches, requiring testing at 125% of the rated depth in both fresh and salt water. These tests are done in still water at room temperature; they do not simulate swimming, diving, or high-pressure sprays.

How to Read an IP Rating

An IP rating like IP67 breaks down as:

• First digit (6): totally protected against dust and other solid particles.
• Second digit (7): protected against temporary immersion in water (up to 1 meter for 30 minutes).
• IPX7: the first digit is replaced with X, meaning the solid protection is not specified, but the water resistance is.
• IP65: protected against low-pressure water jets from any direction, but not immersion.

The IP code does not cover steam, high-pressure jets, or water temperature extremes. A product rated IP67 may fail if used in a hot shower or a fast-moving river.

ATM vs. Meter Ratings for Watches

Watch water resistance is often marked in ATM (atmospheres) or meters. The conversion is simple: 1 ATM = 10 meters of static water pressure. However, the real-world guidance is more conservative:

• 3 ATM / 30 meters: splash proof, rain, hand washing—not for swimming.
• 5 ATM / 50 meters: showering, swimming in shallow water, but not diving or high-impact water sports.
• 10 ATM / 100 meters: snorkeling, swimming, but not scuba diving.
• 20 ATM / 200 meters: professional diving, high-impact water sports.

These ratings assume fresh water at moderate temperatures. Salt water, chlorine, and soap can degrade seals over time, so rinsing after exposure is recommended.

Common Misconceptions and Mistakes

A common misconception is that a 50-meter rating means you can dive to 50 meters. In reality, the rating is a static pressure test, and movement increases the pressure on the seals. For example, a watch rated 50 meters is generally not suitable for swimming because the arm movement increases water pressure beyond the static rating. Another mistake is confusing IPX7 (immersion) with IPX6 (powerful water jets). A product rated IPX6 can withstand high-pressure sprays but may not survive immersion. Also, water resistance is not permanent—gaskets and seals degrade with age, heat, and impact, so a rating is only valid for a new, undamaged product.

How to Choose the Right Water Rating

When selecting a device, consider the actual water exposure it will face:

• Daily use (rain, splashes): IPX4 or IPX5, or a 3 ATM watch.
• Swimming or snorkeling: IPX7 or IPX8, or a watch rated 10 ATM.
• Scuba diving: a watch rated at least 20 ATM, ideally ISO 6425 certified.
• High-pressure cleaning: IPX6 or higher, but check if the product is rated for hot water.

For electronics, IP ratings are more reliable than ATM ratings because they are tested under specific conditions. Always check the manufacturer’s fine print—some IPX8 ratings specify a maximum depth and duration.

Costs and Practical Considerations

Higher water ratings usually increase the cost because they require better seals, coatings, and materials. For example, a basic IP67 smartphone is common, but a dive computer rated for 100 meters costs significantly more due to the robust construction and testing. However, a higher rating does not mean you can ignore maintenance. Gaskets need periodic replacement, and any drop or impact can compromise the seal. Also, water resistance is not covered under warranty for most products if the seal fails due to normal wear.

Safety and Limits of Water Ratings

Water ratings are not a guarantee of safety in all conditions. They are based on static tests in controlled environments. Hot water, steam, and rapid temperature changes can cause seals to expand or contract, allowing water ingress. Additionally, salt water is more corrosive than fresh water, so products rated for fresh water may not survive in the ocean. Always follow the manufacturer’s instructions and avoid exposing devices beyond their rated limits. If a product is rated IP68, it is still not safe for deep diving or high-pressure water sports unless explicitly stated.

Frequently Asked Questions

Is IP68 better than IP67? Yes, IP68 offers continuous immersion at a depth specified by the manufacturer (often 1.5 meters for 30 minutes), while IP67 is limited to 1 meter for 30 minutes. However, the exact conditions for IP68 vary by product, so check the fine print.

Can I swim with a 5 ATM watch? Most manufacturers recommend against swimming with a 5 ATM watch because the movement in water creates pressure that can exceed the static rating. It is safe for showering and shallow water, but for swimming, a 10 ATM rating is safer.

What does IPX7 mean if the first digit is X? The X means the product was not tested for solid particle protection, or the rating is not specified. It only tells you about water resistance, not dust or dirt protection.

Why is my phone not waterproof even with IP68? IP68 means it is water-resistant under specific test conditions, not waterproof. The seals can fail if the phone is dropped, exposed to heat, or the port covers are not closed. Also, water damage is often not covered by warranty.

How do I convert ATM to meters? Multiply the ATM value by 10 to get the static water pressure in meters. For example, 5 ATM equals 50 meters of static pressure, but the practical swimming depth is much less.

Related

• Automation Testing: A Beginner’s Tutorial
• 5G Business Impact: 7 Ways It Changes Work
• Best Multiplayer Games for Chromecast

in p | Pressure rating | m | 50 | 0 | 1000
in d | Depth in water | m | 10 | 0 | 100
out depth | Equivalent depth | m | p | 2
out pressure | Pressure at depth | kPa | d * 9.80665 | 1
out pressure_psi | Pressure at depth | psi | d * 1.42233 | 1