Swimming education in Germany is highly standardized. The "Bundesverband zur Förderung der Schwimmausbildung" (federal association in furtherance of swimming education) consists of different lifesaving and sports organizations and has recently published new examination regulations which highered the standards for swimming badges.
All swimmming instructors in those organizations will tell you that you should permanently keep an eye on your kids and don't let them go to the pool alone until they complete the bronze badge which requires you to swim for fifteen minutes, dive down to two meters and jump into the water. Only after you complete this test you are considered a "safe swimmer".