Don't go swimming with your new iPhone 15, even if it says it's waterproof | ZDNET

'ZDNET Recommends': What exactly does it mean?

ZDNET's recommendations are based on many hours of testing, research, and comparison shopping. We gather data from the best available sources, including vendor and retailer listings as well as other relevant and independent reviews sites. And we pore over customer reviews to find out what matters to real people who already own and use the products and services we’re assessing.

When you click through from our site to a retailer and buy a product or service, we may earn affiliate commissions. This helps support our work, but does not affect what we cover or how, and it does not affect the price you pay. Neither ZDNET nor the author are compensated for these independent reviews. Indeed, we follow strict guidelines that ensure our editorial content is never influenced by advertisers.

ZDNET's editorial team writes on behalf of you, our reader. Our goal is to deliver the most accurate information and the most knowledgeable advice possible in order to help you make smarter buying decisions on tech gear and a wide array of products and services. Our editors thoroughly review and fact-check every article to ensure that our content meets the highest standards. If we have made an error or published misleading information, we will correct or clarify the article. If you see inaccuracies in our content, please report the mistake via this form.

A day at the beach with the Cat S75.

Smartphones barely leave our side these days, and so it's no surprise that the designs of these devices would evolve to cope with being exposed to one of their biggest enemies -- water.

Now, water is formidable in its destruction of electronics. A single drop, or even the buildup of condensation, can destroy a device. Water can cause electrical short circuits that damage delicate components. And don't make the mistake of thinking that sticking your phone in a bowl of rice will help. Even if the device seems to survive its encounter, corrosion can quickly take hold and destroy it over the following weeks or months.

Also: iPhone 15 Pro vs. iPhone 14 Pro: Which model is best to buy?

So far, I've been talking about fresh water, but seawater, thanks to the conductive and corrosive properties of the salt, is even worse. The short circuits are more vicious, and the corrosion can take hold within hours.

I've seen the internals of smartphones and action cameras reduced to oxidized brown sludge after seawater infiltration.

In order to quench our fears of being separated from our smartphones for any length of time, manufacturers started to make their devices 'water resistant' and 'waterproof'.

Also: 5 ways to keep your smartphone working like new, for longer

Of course, anyone can say their technology is water resistant or waterproof, but you really need some reassurance that the device has been tested -- and you need to know the parameters of what it can survive, so you don't get a nasty surprise.

The most recognized rating for water and dustproofing is the IP, or Ingress Protection, rating. This rating is based on international standards and is used to define levels of sealing effectiveness of enclosures against the ingress of moisture and foreign bodies, such as dirt, dust, and sand.

IP ratings consist of two digits. The first digit is the ingress protection rating, with the digits ranging from 0 (or X), which means no protection, to 6, which means the enclosure is dustproof.

The second digit is for moisture ingress protection, and this ranges from 0 (or X), which means no protection, to 8, which means the enclosure can resist extended immersion under higher pressure or at depths generally up to three meters (9.8 feet).

Also: Is a 'water-resistant' power station too good to be true? I tested one to find out

You might also see IP69K being used, which means the item is not only dustproof but can also resist high-pressure water jets and high-temperature spray downs.

So, for example, Apple's new iPhone 15 is rated IP68, with Apple adding it's waterproof to a maximum depth of six meters for up to 30 minutes. The Cat S75 is rated to IP68 and IP69K, while the Blackview BV9800 is rated to IP68, IP69K, and MIL-STD-810H.

But wait a minute -- what's MIL-STD-810H?

This is a U.S. Department of Defense test standard that subjects items to a wide range of environmental factors, such as vibration, shock, extreme temperature ranges, humidity, rain protection, sand and dust ingress, explosive atmosphere, and even fungus.

So, if my device is rated IP68, IP69K, and MIL-STD-810H, is it OK to cannonball into the pool, smartphone in hand? Well, this is where I get cautious.

The first reason is a simple one -- do I trust the rating? If a big company like Apple or Samsung, or companies that make action cameras like GoPro or DJI, say something has been tested to a standard, I trust them. As we move down the line of manufacturers, my trust wanes somewhat.

Also: Battery bad after installing an update? Try these tips

I do a lot of testing of things that claim to be waterproof, and I come across a lot of stuff that doesn't pass muster (which never makes it to these pages).

Another thing to bear in mind is that these tests are carried out on samples that are new. Wear and tear, knocks, dents, and other damage can compromise the seals in a device.

Another issue is the possibility of hidden manufacturing or assembly defects.

Also: 'Liquid Detected in Lightning Connector'? Here's what to do now

Also, if something says it's waterproof, and water gets in, who pays for the defect?

Now, I've heard a lot of tales of woe concerning soaked iPhones, and the response owners get from Apple is varied. Some people get a free repair or replacement, others are told to use their AppleCare+ (if they have it), and others are told to go back to the beach and pound sand. I should add that I'm only getting one side of the story here, so there may be more to the issue, but it's a concern.

Then there's the fact that water -- especially salty, sandy, or dirty water -- is harsh on things like ports and buttons, and sand in a charging port can be a nightmare to get out.

Finally, a smartphone dropped into water can be incredibly hard to find, making recovery tough. Pools are not too bad, although the chemicals added to keep the water clean are potentially worse than seawater. But drop a phone into three feet of water in a river or the sea, and it can be nigh on impossible to find.

Also: The best rugged phones, tested and reviewed

Let's now circle back to the terms "water resistant" and "waterproof". I've tested a lot of gear that falls into those categories, and some technology survives really harsh underwater abuse. But would I take my daily driver iPhone and use it to get some underwater video of tiny, angry fish?

No, I wouldn't. When it comes to smartphones, I take terms like "water resistant" and "waterproof" to cover accidental exposure to water. My year-old iPhone 14 Pro Max is IP68-rated, but I also know it's been dropped a lot, and exposed to heat and cold, which could have compromised a seal or gasket.

It also doesn't escape my attention that Apple hasn't promoted the new iPhone 15 as an underwater camera, and the same goes for most big-name manufacturers. Companies usually mention a device is water resistant or waterproof, show some splashes, and move on to the next part of the presentation.

Now, your mileage may vary here, and you might take your smartphone with you underwater all the time, but it's not something I can recommend. There are just too many downsides.