I understand that to produce a homeopathic remedy requires several steps:
1) Get some of the stuff that causes the illness
2) Dilute it 10:1 with water.
3) Succuss (shake) it .
4) Repeat #2
5) Repeat #3
6) Continue repeating 2 & 3 until you end up with what is well shaken water. Maybe 10 times.
So you find someone who just drowned. The offending agent will usually be whatever water they drowned in. There should be plenty nearby. Get maybe a cup or bottle full. Now you must dilute it with -- you guessed it -- water. Once more you will find plenty readily at hand. Now dilute that water with more water and shake it thoroughly. Take a small amount of the resulting liquid and dilute it with more water, again shaking (sorry, succussing) it vigorously. Repeat this process 10(?) times before administering a sufficient amount to the victim. Here's the rub: If the victim is not conscious, you should not try to get them to swallow the water or even place any water in his mouth. If the victim is conscious, he may not need this treatment, but if he is thirsty maybe you could let him have a few small sips.
Disclaimer: I am not a homeopathic physician. Before you attempt to use this treatment on a drowning victim consult a licensed, registered or certified homeopathic physician.