Pull the battery out of the drone and set it aside somewhere safe and fireproof because lithium batteries can become unstable when damaged and often burst into flames. Also, the more time that your drone has power applied to it, the more damage will be done.
Great! Now, let’s get on with our article.
So, your drone has crashed into a body of water; a lake, the ocean, a swimming pool perhaps. The type of water does matter. You probably weren’t given a choice, but landing in fresh water is way better than landing in salt water. Salt water is highly corrosive and electrically conductive, so the chances for every kind of harm are a lot higher if you land in the ocean than if you land in a lake.
Let’s talk about the major components and the potential risk:
Once the battery is removed, the next step is to stop the corrosive action of the water and any salts in it. We recommend rinsing the drone in isopropyl alcohol (rubbing alcohol) that you buy at the drug store. Isopropyl alcohol is rather inert chemically and it absorbs water, so everywhere it gets in your drone you will be replacing something bad (water) with something less bad (alcohol).
Next, you need to get the alcohol and remaining water out. This involves disassembling the case and removing the flight controller from its enclosure (if that’s how your drone is built). Then everything goes in a warm dry place, with circulating air.
While you have it disassembled, you also need to check for mechanical damage. Hitting water hard can be almost as bad as hitting the ground. Also, many water landings are really secondary crashes, having hit a tree or something else first.
Spin the motors by hand to make sure that they rotate freely. Do the same with the gimbal components.
When everything is nice and dry, and no longer smells like alcohol, you can put it back together.