If your phone fell in the water, or got wet some other way, and you're reading this - STOP! Pull the battery out NOW!
If your phone doesn't have a removable battery (iPhone, LG) you have a fast decision to make. "Do I spend a few dollars to repair the damage I'm about to do by following this advice, or do I throw the phone into the garbage?" TAKE THE BATTERY OUT. If that means cracking the back cover off the phone and cutting one of the wires connected to the battery (the black one if there is one, either if there isn't or both are black), that's what you do. The longer the battery stays in the phone, the more damage occurs. Don't have a wire cutter? Use a pair of scissors or shears or a nail clipper. Try not to let the cutting tool come in contact with anything but the wire you're cutting. A cellphone battery has enough energy stored in it to weld a small piece of steel.
It will cost a few dollars to have the back replaced, and the cut wire repaired. Unless the phone is an old one worth only a few dollars, you're still ahead of the game.
The worst thing you can do to a wet phone is charge it.
The next worst thing you can do is turn it on.
The third worst thing you can do is leave (or put) the battery in. Leaving the battery in a wet phone causes current to flow where it's not supposed to (across wet places), causing damage. The chemicals in the water slowly erode the phone. Even if you dry it, every humid day wets them again, causing more erosion (and corrosion).
The fourth worst thing you can do is just dry the phone off, or dry it off and put it in rice.
Get a non-metallic pan large enough to hold about a quart of alcohol, plain old 70% rubbing alcohol. (A glass meat loaf pan is about ideal for most phones, but a Tupperware or other plastic container is fine.) Put the phone (the battery has been removed) in the alcohol and swish it around vigorously for about 5 minutes. You want to wash any minerals, dirt, impurities, etc., out into the alcohol. Don't worry about wetting the phone - alcohol isn't water, it absorbs water. It's actually drying the phone.
After about 5 minutes of this, drain the phone, dump the alcohol (it's got water, dirt, minerals, etc. from the phone in it), replace it with fresh alcohol and repeat for another 5 minutes. Then one more time. Three baths in all.
Wipe the battery down with alcohol on a paper towel or cloth. The battery is sealed, you just want to keep from putting any crap into the phone when you put the battery back in.
Put the battery and the phone into a container of UNCOOKED rice. Some people use a plastic bag, but I prefer a gallon jar or a LARGE plastic container that can be sealed. Make sure the phone is completely covered on all sided by the rice. Put the battery in there too - not touching the phone, but covered by some rice. Seal the container. Leave it for a week. (After that, seal the rice in 2 plastic bags and throw it out. The alcohol it absorbed makes it poisonous to animal life [and bacterial life too]. Check with your local drug store (Chemist in Old Blighty) about local laws regarding disposing of rubbing alcohol-soaked absorbents. Some places require you to contact your sanitation people, so it doesn't end up in the landfill, killing hundreds of birds.)
If you immediately remove the battery, you have a 50-50 chance of saving the phone, but I've saved phones that were in a lot worse plasces than a lake or a washing machine. Toilets are some of the cleaner places I've rescued phones from (wearing 2 pairs of surgical gloves and elbow-length rubber gloves). If the water is clean, and you remove the battery within seconds of the phone getting wet, your chances are about 99%. If it's ocean water, sorry, but if the phone fell into the ocean without having a battery in it, it's probably too late. Ocean water (any water with a lot of electrolytes in it) is as bad as charging the wet phone - it does the same damage. By the time you get home, even 5 minutes, the phone is well on its way to being electronic scrap.
After a week in rice, the phone may turn on and seem to work, only to start failing over the coming weeks. That means that there was still some impurity that started causing a short and eventually something got fried. That usually means a new motherboard and other new parts, maybe a screen. Then you have to get a repair estimate and decide whether it's worth putting that much money into that phone. New motherboard in an LG G2? Sure. $50 into a Samsung Precedent? You can buy one new for that price. Compare the price of the repair to the price of outright purchase of the phone. (It's not the subsidized price you paid, if you're in the US. That $49 phone actually costs a few hundred dollars. Even one of those "free" phones is about $100.)
If you're going to be near water, not only on a boat, but in a downpour, or hiking near a stream, get 2 zip-lock bags large enough to put the phone in. Put the phone into one of them and zip it shut. Put that one into the second bag, zipper-first. Leave some air in the second bag - not blown up, just not all sucked out either. (It'll help keep the phone from sinking too fast.) Zip the second bag. (The best ones are the ones in which the plastic of the bag itself is the zipper, not the ones with the little plastic "zipper" you run from one end to the other - those are NOT waterproof.) You can hear, talk, read the screen, press the screen and press the buttons through the bags. You may drown, but your phone will be safe.
If you're really going to be around deep water - like on a boat - use an old boater's trick. Wrap some thin wire around a corner of the bags - tightly. Put the end through a "popper" or fishing float or some other large piece of cork. They make them for keys, and boating stores sell them. Use one fot the bags on your phone. (Do NOT punch a hole in the bags to hold the wire.) Experiment with how much bouyancy you need for that phone before you drop it into 250 feet of water filled with feeding whales. You want the cork to stay at the surface when the phone is in the water. If it sinks in the 2 feet you're testing in, you can reach in and get it back - and use a larger float.
(Copyright all years, by the entire planet of Pern and the Rukbat stellar system, so there. Permission is granted to repost this anywhere on the internet, as long as credit is given to Rukbat as the author.)
