Drowning cuts off the air or rather the oxygen of the air from the lungs, producing asphyxia or suffocation. Human life under water cannot last more than a few minutes, yet even when a person has been under water for half an hour prompt attempts at resuscitation by artificial respiration should be made.
Be sure to have victim's head a little lower than his body, and turned to one side so that the pressure on his chest when performing artificial respiration will empty the water from his lungs without flowing back at inspiration.
Make certain that there are no dentures or other obstructions to breathing in his mouth. Call for others to help you attend to all that and to call a doctor while you continue with the artificial respiration.
Better not attempt the heroic in rescuing a drowning person unless you have been trained in the work, or there might be two drowned persons instead of one. Throw out a rope , a plank or anything that will float for the drowning peprson to hold on to and be towed in. If you can manage a rowboat well, go out in a boat, help him in at the stern.
If you try to pull him in by a rope, do it slowly lest he lose hold. If the breathing when rescued, make him lie down anyway. He must not be allowed to stand or sit. Wrap him well, and give him hot drinks. Keep him at rest long enough to recuperate from the exhaustion and shock.