When did you allow your kids to swim in the backyard pool without adult supervision?

I have two boys, ages 13 and 11. I am normally pretty laid back compared to their friends parents. I don't hover over them and I allow them to have a greater sense of independence. They get home and hop on their bikes to ride with their friends. I don't need to know where they are every second of the day. I say all this to say that I am not normally overprotective of my boys.We hope to open the pool within the next couple of months and I was wondering if they are old enough to swim without adult supervision. They are very close and pretty much always swim together or with a friend, but do they still need adult supervision every time?They both love to swim and spend most of their summer in the pool. It seems like an inconvenience to have to go out their every time they are in the water, but I had a really close friend die while swimming unsupervised when we were kids. He was 10 at the time. My boys are both really strong swimmers. One of them is actually on a swim team, but it's still a concern I have. Is it okay if they are swimming together? Should I supervise if they have friends over (teen and tween boys tend to do stupid things when packed together)? Am I being too overprotective?If it matters, the pool in 10 feet deep on one side and 4 feet deep on the other. via /r/Parenting http://ift.tt/2mzvnW8