At about 4 p.m., emergency crews responded to the pool, located in the 1200-block of East Algonquin.
The man was swimming with his 8-year-old daughter, according to Schaumburg police. Authorities do not believe alcohol was a factor, but were immediately unsure how he ended up on the floor of the nine-foot deep pool.
Two residents rescued the man and performed CPR. The man was taken to Northwest Community Hospital.
No lifeguard was on duty, police said.