[ntoronto]

> Also, how do you differentiate the drowning response from someone that's just bad at treading water and floats low in the water?

Watch the face, arms and legs, and water surface. A swimmer in distress has his mouth as high as possible, may be flailing a little with his arms, barely kicks (if at all), barely disturbs the surface of the water, and goes under repeatedly.

But as a lifeguard, I helped weak swimmers, and then requested very firmly that they stay in shallow water. I also took their names so I could get their attention quickly if they wandered too close to the deep end.