Do pools spawn zombies? In static mode, this is an annoyance, as even when you clear a place out, zombies still come out of the pool. If there’s a static amount of zombies in the pool, nevermind. But if there isn’t, fix it.
Swimmer Zeds are new in 0.8. Shouldn’t spawn Dynamically from pools, though, and if they do it’s a bug.
(You can’t see them whilst they’re underwater, so perhaps it looks like they spawn? Clear 'em out, and then let off a shotgun or something?)
Zombies don’t spawn in pools (assuming you have static of course) but they can wander into the pool and not wander out again until later and IIRC you can’t see them while they are underwater like that (unless you yourself dive underwater).
Zombies can now chase you into deep water. Swimmer Zombies are the only ones that spawn in pool areas, but they don’t do so dynamically when static spawn is on (it’s identical to the child zombies in parks). You just may not be able to see them until they come after you, that’s all.