Just how water-resistant is that box filled with electricity? Adrian Kingsley-Hughes/ZDNET I remember a time when you wouldn't dare let water anywhere near a smartphone or power bank, as it would almost certainly mean disaster. Today, however, most smartphones are designed to be water- and dust-resistant to some extent, and even gadgets like power banks and portable power stations are following suit. Also:The best portable power stations you can buyBut how can you determine exactly how water- and dust-resistant a device is? And what's the difference between something being water-resistant and truly waterproof? IP ratings explainedThis is where IP ratings come into play. IP, short for Ingress Protection, is an international standard used to measure a device's resistance to water, dust, and other foreign objects. It's expressed in the form of IPXX, where each "X" represents a numeral. The first digit indicates protection against solid particles, like dust, while the second digit measures resistance to liquids. The numbers for dust range from 0 (not dust-resistant) to 6 (dust-tight), while the numbers for liquids range from 0 (no protection) to 9 (protection against high-temperature, high-pressure water jets). If an X appears in the rating, that indicates unknown, meaning a test wasn't carried out. For example, IPX5 means that no test was carried out for dust intrusion. IP RatingDust Protection (First Digit)Liquid Protection (Second Digit)XUnknownUnknown0No protection against dust or solid objectsNo protection against liquids1Protection against solid objects larger than 50 mm (e.g., hands)Protection against vertically falling water drops2Protection against solid objects larger than 12.5 mm (e.g., fingers)Protection against vertically falling water drops when the device is tilted up to 153Protection against solid objects larger than 2.5 mm (e.g., tools, wires)Protection against water sprays at an angle of up to 604Protection against solid objects larger than 1 mm (e.g., small wires)Protection against water splashes from any direction5Limited protection against dust (dust might enter but won't interfere with operation)Protection against low-pressure water jets from any direction6Complete protection against dust (dust-tight)Protection against high-pressure water jets from any direction7N/AProtection against temporary immersion in water (up to 1 meter for 30 minutes)8N/AProtection against continuous immersion in water under conditions specified by the manufacturer (e.g., depth and time)9N/AProtection against high-pressure, high-temperature water jetsThis standardized system eliminates the ambiguity often caused by marketing claims, providing a clear and reliable measure of durability. IP-rated devicesMost smartphones, for example the iPhone 16 or the Samsung Galaxy S25, are rated IP68. But while both are dust-tight, the water resistance varies. The iPhone can withstand being submerged up to 6 meters deep for up to 30 minutes, but Samsung says that the Galaxy S25 is only good for 1.5 meters of freshwater for up to 30 minutes. Pair your smartphone with apower bank like this IP68-rated Klarus K5, and you've got the perfect outdoor setup. There's also the Shargeek 170 power bank, which is rated IP66, meaning it's dust-tight and can handle high-pressure water jets from any direction, but it's not made for submersion.Then there's theDT Research tablet is rated IP65, rated IP65, so it's dust-tight and can handle low-pressure water jets from all sides. This tablet can take a real soaking. Adrian Kingsley-Hughes/ZDNET And if you're looking for a power station, the Bluetti AC60P is rated IP65 too, making it great for outdoor use. Just keep in mind that the manufacturer doesn't recommend using it when it's wet. This power station is perfect for outdoor use. Adrian Kingsley-Hughes/ZDNET Other ratings to knowIncreasingly, I come across devices that are IP69K-rated, such as ruggedized smartphones. This rating means the device is not only dust-tight but also resistant to high-pressure water jets (up to 100 bar or 1450 psi) at high temperatures (up to 80C or 176F). Devices with this rating are built to endure the harshest conditions. Some gadgets might also claim to be MIL-STD-810-rated. This is a United States Military Standard developed by the US Department of Defense to test and evaluate the durability and environmental resilience of equipment. It covers a wide range of conditions, including extreme temperatures, humidity, vibration, shock, sand, dust, and even explosive atmospheres. The standard also allows tests to be tailored to the specific environmental conditions the equipment is expected to face. This Ulefone Armor 25T Pro ruggedized smartphone claims to be MIL-STD-810- and IP69K-rated. Can you trust these ratings?Well there are three factors at play here. Also: The best power banks you can buyThe first is whether you trust that the manufacturer making the claim has actually tested the device, tested it properly, and been honest about the results. While I can't carry out scientific tests, I've had plenty of experience exposing gadgets to dirt, dust, and water on a regular basis. From my experience, while you can generally trust the big-name manufacturers, there's no shortage of companies that claim an IP rating, but their products fail to deliver on that promise. Another factor to bear in mind is that sometimes flaps and covers are used to give the device dust and water resistance, and these will need to be secured in order for the device to achieve the stated rating. These rubber flaps are a vital part of the tablet's IP protection. Adrian Kingsley-Hughes/ZDNET And finally, there's wear and tear. A product that's new might be dust-tight and water-resistant, but after a few years of drops, bumps, and exposure to chemicals such as sunscreen or insect repellents, the gaskets and seals can weaken, and that resistance can be lost. So, that's IP ratings in a nutshell. They're incredibly useful for understanding the limits of a device, but keep in mind that not all gadget makers are entirely honest, and even if they are, wear and tear can still affect a device's resistance over time. Featured