I'm sure much has changed in recent years, but even 17 years ago, we had to have a perc. test, permit from the county, and an inspection by the county sanitary guy (I've forgotten his exact title). So, yes, you definitely need to check with your county. Of course, unless you're actually doing the installation yourself, the person you hire should be familiar with all the requirements. And some of the requirements may be absolutely ridiculous. If a perc test comes back bad, you have to use an aerobic system instead of anaerobic, but if you plan to use the aerobic system to start with . . . well, we still had to pay for the perc test which took the guy at least 2 or 3 minutes. But maybe that was just the county we were in instead of statewide.