A water damage indicator, known by a variety of other names, is a small device found inside many electronic devices that permanently changes color when it comes in contact with water or other liquids. Manufacturers and repair services use the indicators to quickly check a device for water damage, which is not covered by most warranties. They are commonly found in cell phones, portable music players, laptop computers, and other types of electronics. Water damage indicators can be controversial; some consumers claim they are unreliable and used to deny warranty coverage for devices that have not suffered water damage.

Manufacturers, the press, and consumers have a number of different names for water damage indicators. These include water damage tape, water damage sticker, water contact indicator tape, liquid submersion indicator, and liquid contact indicator. Regardless of what they are called, these indicators all work in the same way: when exposed to water or liquids containing water, they change color. Most look like small stickers or pieces of tape and include a special water-sensitive dye that turns from white to red or pink when exposed to liquid.

It’s common to find a water damage indicator in a cell phone, but many other electronic devices such as laptops, portable music players, and digital cameras have them as well. The indicators can be located in many different positions such as headphone ports, data ports, under batteries, or inside a device where water can do the most damage. Many devices include more than one water damage indicator; there are often in two or more different locations.

Since most warranties only cover defects in a product and not damage caused by accidents, a water damage indicator is frequently used as a quick way of determining if a customer’s device is eligible for repair under warranty. The indicators can be advantageous for companies because they provide very quick evidence of water damage in a particular product. A technician can, for example, inspect the indicator of a water damaged cell phone and quickly determine that it would not be eligible for repair without having to disassemble the phone.

Some consumers have complained that these types of indicators can be set off even without being immersed in water. Anecdotal evidence of a water damage indicator changing color when exposed to small amounts of sweat, rain, or even humidity can be found on countless websites and from a few media outlets. One major electronics company was hit with a class action lawsuit in April 2010 over the use of allegedly unreliable indicators in the headphone and data ports of its mobile devices. Manufacturers claim the sensors should not change color when used according to a product’s environmental guidelines.