realityblurred is reporting that Survivor 21 and 22 may be filmed back-to-back in Nicaragua, with seasons 23 and 24 taking place in Caramoan in the Philippines.

CBS has ordered more editions of its Emmy Award-winning reality franchises-SURVIVOR and THE AMAZING RACE-for broadcast in the 2010-2011 season. SURVIVOR will return with two more editions, marking the 21st and 22nd installments of broadcast television’s longest-running reality competition series.

Survivor is now casting for seasons 21 and 22, although it has not yet been officially renewed by CBS, nor has Jeff Probst announced whether or not he’s returning as host, since his contract expires at the end of season 20. However, it’s typical for the show to start casting before being officially renewed, and if the show is renewed, pre-production would likely begin in January.