Your Samsung Galaxy S3 android phone has water damage indicators to tell whether your phone was in contact with water or any liquid. It is difficult to find these indicators as they are different for each carrier.
If your android phone was dropped in water, You can try to repair your water damaged android phone. You can follow below instructions to look for water damage indicators and see if they turned from white to red.
How to check for Water Damage Indicators on Samsung Galaxy S3 T-Mobile/Verizon/Sprint?
1. Turn off your android phone. Remove back cover. Remove Battery. You can see an indicator behind the battery as shown below. It should be in white color.
image credit: ifixit
2. There is another indicator on the batter itself. Damage Indicator sticker on the battery is solid white or white with small x’s covered with red. If the sticker comes in contact with water, It turns to red, purple, or pink.
image credit: samsungupdate.com
How to check for Water Damage Indicators on Samsung Galaxy S3 AT&T?
As per GoGazelle, AT&T Galaxy S3 has indicator just to the left of the battery approx 2/3 the way up from the bottom of the phone. This is a normally white dot indicator. This will turn red if it comes in contact with any liquid.
AT&T Samsung Galaxy S3 also has water damage indicator sticker on the android phone battery as described in #2 above.