While it's no news that water and electronic devices don't mix, Apple has of late rolled out an interesting and little-known design feature: the liquid submersion indicator (LSI). Now integrated into the design of all Apple laptops, iPods, and iPhones, the LSI reveals whether or not its host device has been subjected to liquid damage.
As Apple clearly states on its support pages, "Liquid damage repair is not covered by the Apple one year limited warranty or the AppleCare Protection Plan." Thus, if your MacBook Air or iPhone receives an accidental dunking, you're not going to be able to convince Apple to repair it for free. Not as long as you have an iPhone or an iPod manufactured after 2006, or any laptop produced since 2008 - all these models include an LSI.
For the iPod and iPhone, the liquid submersion indicator is usually found in the headphone jack. Examining the inside of the jack with a magnifying glass reveals a white dot at the end of the passage. This dot turns half red or pink if the device has been submerged in liquid. For the iPhone 3G the indicator is located on the bottom of the connector housing, right under the 30-pin dock connector.
While iPod and iPhone owners can view the LSI without disassembly, the same is not true for the MacBook line. Apple doesn't say where the LSIs in the laptops are exactly, but AppleInsider published a diagram claiming to show their locations. The four LSIs in the MacBook, MacBook Pro, and MacBook Air are spread out in various points below the keyboard where they'd work well for detecting spilled liquid. Again, normally white, the indicators turn red when exposed to moisture, but even getting to them to determine if there was liquid damage can reportedly take a technician up to 2 hours.
We can only assume that Apple's repair technicians had sufficient evidence of people returning liquid-damaged devices under phony pretenses to warrant the creation and implementation of these indicators. It's also likely that the cost to incorporate the LSIs in the new laptop models was small enough to make it worthwhile for cutting down on repair fraud.
On the user end, the most obvious concern is that these LSIs will somehow indicate liquid damage when the device hasn't been dunked. In particular, people living in extremely humid climates have voiced concern that the indicators could misinterpret environmental conditions and prevent them from receiving deserved support. How much of a concern this should be is hard to say, given that the information available on the nature or composition of these indicators is slim. We did find a note from an Apple repair technician passing on the claim from Apple that the indicators are "very accurate" and "will not be affected by humidity or environmental factors."
More troublesome might be actual exposure to liquid that activates the LSI but does not, at that point in time, cause the device to fail. Should the device need repair in the future for a seemingly unrelated reason, that repair may be denied because of the LSI. Water, for instance, doesn't itself necessarily damage electronics, but can cause electrical short circuits that will. So if power is removed instantly, and the device is allowed to dry, it may be fine. Unfortunately, other liquids like coffee and soda may contain corrosive substances or leave behind conductive residues even after the liquid has evaporated. In such cases, the device may seem to work properly for some time after the spill, but gradually become flakier.
The moral of the story? You already know to try to keep liquids away from your devices, but if the worst does come to pass, you'll just have to own up to the mistake and pay for repair or replacement unless you have computer insurance coverage from a company like Safeware.