Here’s how Apple tells if you’ve dropped your iPhone in water

Image: Maria Diaz / ZDNet

While the most common way for a smartphone to fall out of action is by damaging the screen, a close second is dropping the smartphone into liquid (or spilling something on it).

It is a common problem that hardware manufacturers fit small devices that react to water.

Called liquid contact indicators (LCIs), these are small color-changing stickers that are placed in various places inside a device usually near ports, SIM card slots and other entry points for water.

These are used not only to indicate whether water has actually made its way into a device, but also to know how far the water has spread.

LCI is used in a wide variety of devices, from smartphones and tablets to portable game consoles.

Anything is likely to make people skip the toilet.

Here are the LCI stickers that Apple used in the iPhone a few years back (they were used from the iPhone 8 to the iPhone X). Apple still uses LCI stickers in its devices, but they differ in size and location.

Liquid Contact Indicator Sticker

These things are smaller, smaller than a grain of rice.

Adrian Kingsley-Hughes

When they encounter water, they turn from white to red. What’s happening here is that exposure to water melts the white coating on the top of the sticker, which in turn reveals the red color on the bottom.

Over the years, I’ve had some questions about LCI, and what will trigger them and what doesn’t.

First, note that the process is irreversible, and drying the LCI will not make it white again.

Another question is whether solvents such as isopropyl alcohol would trigger LCI. I’ve tested both 99% and 70% isopropyl alcohol, and neither seems to trigger LCI.

Some people think that if you soak LCI in isopropyl alcohol, it will not turn red when it comes into contact with water. it is not true; LCI remains active.

Do Fizzy Drinks Trigger LCI? You bet they do!

Lastly, does living in a humid environment trigger LCI? I put in a bag, breathed it so that the condensation was in the bag, and set it so the LCI didn’t touch a surface with condensation. After more than an hour, the LCI remained white.

This LCI has been inside a bag with high humidity for over an hour and it hasn’t turned on

Adrian Kingsley-Hughes

If you have an iPhone, you can see an LCI by removing the SIM tray and looking into the slot for the white dot (hopefully, it’s still white, anyway!).

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