Johnny would have only had to inhale four ounces of water -- about six teaspoons -- to drown, and even less to injure his lung enough to become a victim of secondary drowning...
"If your child comes out of the pool and seems sleepy or lethargic, watch them very, very closely... Rush them to the hospital or call 9-1-1 immediately."
ADDED: There are actually 24 teaspoons in 4 fluid ounces.
IN THE COMMENTS: Read what Pogo says. He's a doctor.