Your toddler dropped your smartphone in the toilet (again). But if it’s water resistant, you’re in the clear — right?

Maybe.

Before you get too close to the toilet, or the ocean, lake or pool with your smartphone, smartwatch or digital camera, learn what “water resistant” really means.

Water resistance: all the rage

If you haven’t come across a tech product with a rating for water resistance just yet, it’s not hard to find one. Sony’s latest smartphone, the Xperia Z3+, for instance, is touted for its water resistance. Samsung, another popular smartphone maker, is also big on providing water-resistant products. The company has smartphones, tablets and wearable devices that can supposedly withstand a drenching.

Other, smaller companies, like GoPro, Garmin and Panasonic, offer “rugged” devices that the companies say can withstand a beating and shower.

Even the Apple Watch claims some water resistance.

But how water-friendly are these products? Can they withstand a dunk in the pool or just a spritz from passing a sprinkler?

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What IP ratings means

To claim their products are water resistant, a company may have them certified by a third-party independent organization governed by the International Electrotechnical Commission (IEC), an international body that sets standards on everything from how a product should be secured to how it’s graded in its ability to protect against harmful environments. In the United States, UL (Underwriters Laboratories) is an independent testing laboratory that can test water resistance based on UL or IEC standards depending on how a manufacturer chooses to have a product evaluated.

The IEC’s standards are used by third-party certification organizations — or the device-makers themselves — to assign to products an Ingress Protection Rating, or IP rating, based on their performance on tests.

The IEC’s standards include a scale for waterproofing that ranges from 0 to 8. A 0 means the device has no protection against water, while an 8 says a device can be submerged in water more than a meter deep and still work. The standards also include scales for other features, such as dust resistance. When scoring is completed, devices will receive a rating of, say, IP68, with the 6 representing its dust resistance and the 8, its water protection.

The Sony Xperia Z3+, for instance has a rating of IP68.

But an 8 means the device was tested only against “rain, splashing, and accidental submersion” for an unknown amount of time. Who’s to say how a product with an 8 rating would perform when, say, it’s left under a running faucet for three minutes, or when you swim with it in the deep end?

Under IEC standards, companies are allowed to test their devices for only one measure. Testing for a 7 rating (and getting one), for instance, means the device can withstand immersions of up to 1 meter. A 6 means it can withstand high-pressure water jets from any direction. An 8 doesn’t mean, however, that the device has passed measures 1 through 7, though one could assume it would hold up under those circumstances.

It’s also worth noting that IP ratings are based on freshwater analysis. Salt water’s corrosive effects on your device may be a whole different story, one that IP ratings don’t cover.

Complicating matters further, some companies, including Apple, perform their own testing and make claims based on those results, which aren’t necessarily confirmed by a third party. So you’ll have to take the company’s word for how waterproof the device is.

If you’re willing to take the gamble, go ahead and jump in the lake with your new device. But except death and taxes, nothing in life is guaranteed, and that includes water resistance under every circumstance.

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Don Reisinger is a longtime technology journalist and product reviewer.