Water Resistant vs. Waterproof: What's the Real Difference?

You see the word "waterproof" stamped on a watch case and assume the device can handle a dive into the deep end. That assumption often leads to a foggy dial and a ruined movement. Water is the universal solvent, capable of rusting gears and destroying lubrication in moments.

Most people use "waterproof" and "water-resistant" interchangeably. The difference between them actually determines whether your watch survives a swim or drowns in the pool. A true understanding of these ratings protects your investment and helps you pick the right components for your next build.

The "Waterproof" Myth

Marketing often plays tricks on us. The Federal Trade Commission actually banned the use of the term "waterproof" in the watch industry in the 1960s. No watch is truly impenetrable forever.

Rubber gaskets and O-rings create the seals that keep moisture out. These components dry out, crack, or harden over time. A watch that is perfectly sealed today might leak in two years if the gaskets degrade. We use the term water-resistant because it describes the watch's ability to keep water out under specific conditions, not all conditions.

Decoding ATM Ratings

You will usually see water resistance measured in "ATM" (Atmospheres) or meters. One atmosphere roughly equals the pressure found at 10 meters of depth.

Labs test these ratings using static pressure. The watch sits still in a pressurized tank. Real life involves movement, which changes everything. Here is what those numbers actually mean for your daily wear.

3 ATM / 30 Meters

A rating of 30 meters sounds like a lot. In reality, a 3 ATM watch can handle rain, washing your hands, or accidental splashes. Submerging it in water is a bad idea. The seals are minimal and designed only for incidental contact.

5 ATM / 50 Meters

Brief immersion usually poses no threat here. You can likely swim in a shallow pool with a 50m watch. Vigorous swimming or jumping off a diving board creates pressure spikes that might breach the seals.

10 ATM / 100 Meters

Real aquatic activity becomes possible at this level. Snorkeling, swimming laps, and boating are safe activities for a 10 ATM watch. This rating offers a solid balance for a daily driver that might get wet.

20 ATM / 200 Meters

Serious diving requires this level of protection. Watches rated to 200 meters often feature a screw-down crown and thicker case backs to withstand heavy pressure. You can trust these builds for recreational scuba diving.

Check out our Seiko NH36 Movement Kits, which act as the heart of many reliable, water-resistant builds.

IP Ratings Decoded: Your Guide to Water Protection

Now, let's talk about IP ratings. IP stands for Ingress Protection, and it's like a report card for how well a device resists water and dust. You'll see it written as something like "IP68". Here's how to read it:

• The first number (0-6) is for dust protection.

• The second number (0-9) is for water protection.

So, an IP68 rating means the device is great at keeping out dust (6) and can handle being submerged in water (8). Here are some common water ratings you might see:

• IPX4: Can handle splashes from any direction. Think of it like wearing a raincoat.

• IPX7: Can be submerged in 1 meter of water for 30 minutes. Like a snorkel mask.

• IPX8: Can go deeper or stay underwater longer. The exact details depend on the manufacturer.

IP Ratings vs. ATM

Smartphones and smartwatches often carry an "IP" rating, like IP68. Mechanical watches rarely use this system.

IP (Ingress Protection) ratings tell you two things. The first digit (0-6) measures protection against solid objects like dust. The second digit (0-9) measures protection against liquids.

• First Digit: A 6 means the device is dust-tight.

• Second Digit: An 8 generally means the device can withstand continuous immersion beyond 1 meter.

Electronics manufacturers prefer IP ratings because they account for dust. Watchmakers prefer ATM because it accounts for the immense pressure changes found in deep water.

Key Differences Between Water Resistant and Waterproof

Let's break it down in simple terms:

1. Water Resistant devices can handle some water, but have limits. They're like a good umbrella - great for rain, not for swimming.

2. Waterproof (or highly water resistant) devices can handle more water for longer periods. They're more like a wetsuit - designed for serious water activities.

Here's a quick comparison:

• Water Resistant (3-5 ATM or IPX4-IPX6):Good for: Everyday wear, light rain, washing handsNot good for: Swimming, diving, water sports

• Waterproof / Highly Water Resistant (10+ ATM or IPX7-IPX8):Good for: Swimming, snorkeling, water sportsNot good for: Deep sea diving (unless specifically rated for it)

How Dynamic Pressure and Heat Affect Water Resistance

A static pressure test in a lab does not account for a freestyle swimming stroke. Moving your arm through water creates dynamic pressure.

The force of the water rushing against the watch adds to the static pressure of the depth. A cannonball into a pool exerts a massive force on the gaskets instantly. That sudden spike can force water past seals that would otherwise hold tight.

Heat poses an even bigger threat. Hot tubs, saunas, and hot showers are the enemies of mechanical watches. Metal cases expand when hot. The glass crystal and rubber gaskets expand at different rates.

Microscopic gaps open up during this expansion. Soap and shampoo also strip the silicon grease that keeps your gaskets supple. The result is a compromised seal and a rusty movement.

Maintaining Your Own Seals

Water resistance is not a permanent feature. You have the power to maintain it yourself.

Building your own watch gives you a massive advantage here. You know exactly where the seals are.

• Inspect the Gaskets: Check the rubber O-ring on the case back whenever you open the watch. If it looks dry or cracked, replace it.

• Apply Grease: A small amount of silicon grease on the gasket and crown seals ensures they remain hydrophobic and water-tight.

• Secure the Crown: Always ensure the crown is fully pushed in or screwed down before getting near water.

Our All-In-One Watchmaking Kits include the guidance you need to install these components correctly from the start.

Your watchmaking story begins with a single screw.

Understanding how your watch resists water is just the first step. Building one teaches you how to master the mechanics behind the dial.

Browse our collection of watchmaking kits to find your perfect project.

Start building today.

How to Choose the Right Level of Protection

Picking the right water protection is like choosing the right coat for the weather. Here's a simple guide:

1. For everyday life (occasional rain, hand washing): Look for 3-5 ATM or IPX4-IPX6 ratings.

2. For swimming and water sports: Aim for 10 ATM or IPX7-IPX8 ratings.

3. For diving or extreme water activities: You need specialized gear with very high ratings (20+ ATM).

Rotate® makes it easy with their kits. The Knight Kit (5 ATM) is perfect for daily wear, while the Cabot Kit (10 ATM) is great for water enthusiasts.

Explore Rotate® DIY Watch Kits

Why IP Ratings Matter More Than Marketing Terms

When you see words like "waterproof" on a product, it's hard to know exactly what that means. But IP ratings are different. They're based on specific tests:

• IP67 devices are dunked in 1 meter of water for 30 minutes.

• IP68 devices go even deeper, often up to 3 meters.

These tests give you a clear picture of what your device can handle. It's like having a weather forecast instead of just looking out the window - you know exactly what to expect.

How to Maintain Water Resistance: 4 Simple Tips

Even the best water resistant gear needs some care. Here's how to keep your devices safe:

1. Avoid extreme temperatures. Heat can make seals expand, and cold can make them crack.

2. If you've been in salt water, rinse your device with fresh water afterward. Salt can corrode metal and damage seals over time.

3. Check the seals once a year. If you're using a Rotate® kit, they include replacement gaskets to keep your watch in top shape.

4. Follow the care instructions. For example, don't press buttons on your watch while it's underwater, even if it's water resistant.

Build Your Own Water-Resistant Watch

With Rotate® kits, you can create a watch that matches your lifestyle. Whether you choose the Knight (5 ATM) for everyday wear or the Cabot (10 ATM) for water adventures, you'll get:

• A high-quality Japanese movement (Seiko NH05 or NH36)

• A sturdy stainless steel case with proper gaskets

• Clear instructions to ensure your watch is properly sealed

Wrapping It Up

Understanding the differences between water resistant, waterproof, and IP ratings helps you make smart choices about your gear. Whether you're building a watch with Rotate® or buying a new phone, these ratings are your guide to keeping your devices safe from water damage. Ready to create a watch that fits your lifestyle?

FAQs

Q1. What's the real difference between waterproof and water-resistant?

Water resistant items can handle some water exposure, while "waterproof" (now usually called highly water resistant) can handle more. For example, a 5 ATM watch resists splashes, while a 10 ATM watch is suitable for swimming.

Q2. How can I find out my device's IP rating?

Check the product packaging, manual, or manufacturer's website. If you can't find an IP rating, the device probably isn't tested for water resistance.

Q3. Is it safe to swim with an IP67-rated device?

IP67 means the device can survive being submerged in 1 meter of water for 30 minutes. It's okay for accidental dunks, but not designed for swimming. For swimming, look for IP68 or 10 ATM ratings.

Q4. Can I shower with a 5 ATM water resistant watch?

While a 5 ATM watch can handle some water exposure, it's best to avoid showering with it. Hot water and soap can degrade the seals over time. It's safer to take it off before showering.

Q5. Do Rotate® watch kits come with everything I need for water resistance?

Yes! Rotate® kits include all necessary gaskets, silicone grease, and detailed instructions to ensure your DIY watch is properly sealed against water.

Q6. What does an IP68 rating mean?

An IP68 rating indicates a device is fully dust-tight (the "6") and can withstand continuous immersion in water beyond 1 meter (the "8"). Manufacturers define the exact depth and time duration, but it generally implies the device survives accidental drops in water.

Q7. Can I swim with a 30m water-resistant watch?

No, avoiding swimming with a 30m (3 ATM) watch is the safer choice. The rating protects against splashes, rain, and hand washing. The pressure created by swimming strokes can easily breach the seals of a 30m watch.

Q8. Does water resistance last forever?

No, the seals degrade over time. Rubber gaskets eventually dry out and lose their elasticity. Testing your watch's water resistance or inspecting the gaskets every year ensures your timepiece stays safe.

Q9. Why shouldn't I wear my watch in the shower?

Hot water causes the metal case and rubber gaskets to expand at different rates. That expansion creates gaps where moisture can enter. Soap and chemicals also break down the lubricants that protect the seals.

Q10. What is the difference between an ATM and a Bar?

ATM and Bar measure pressure and are essentially the same for watch usage. One ATM equals approximately 1.013 Bar. Both units represent roughly 10 meters of water pressure, so 10 ATM and 10 Bar both indicate 100m water resistance.

Q11. Can I fix a foggy watch myself?

Yes, you can often fix this yourself. Fog indicates moisture has breached the case. Opening the case back to let the movement dry out is the first step. You should then check and replace the gaskets to prevent rust and future leaks.