If you are in Sumter County, you are only allowed to water twice a week, per the Southwest Florida Water Management District (
Welcome to the Southwest Florida Water Management District Home Page). If you are in Marion and most of Lake counties, you fall under the St. Johns River Water Management District (
Home of the St. Johns River Water Management District). I believe they also require twice a week watering, but you can find out for sure at that website.
I'm amazed at how few people know about these restrictions, let alone what day/time they are supposed to be watering.