If there's one thing I hate is lake, river and beach water. I watched too many documentaries about bacterias and possible death just by swimming into the lake. I mean though we can die anytime but catching up some nasty bacteria and worms from lake are probably the worst. And yeah, some river here has crocs and giant fishes that could harm you. I really would never trust the lake, river or beach here unless the water is really pristine and you can see everything around. Otherwise, do not swim.
That's why, I avoided the pool during peak hours. I go to the pool either very early in the morning or very late in the evening. Now that I am more comfortable, I swim only in the athletic's pool. It has better filtering system and seems the water is different from the beginners pool.