[matthewsim]

I've almost survived the first Massachusetts winter in my 2005 25' International CCD. I'm hooked up to a septic system, but my black water tank is no longer draining properly. It only drains very slowly and has backed up all the way into the toilet. My gray water tank is draining fine. My guess is that either the black water tank itself or its outflow pipe is blocked up. I've tried the mild enzyme-based septic tank treatments without success. My only thought is to try something more serious, Drano or the like, but the Airstream manual has made me paranoid about using something so corrosive in the system. Should I not worry about this? Is there something else I can try?

Thanks for your help!