lil sis,
I imagine if your home is at a level high enough above the downhill manhole covers, the fluid would naturally flow out at its lowest point if the cover is off (if there is even access to the sewage lines).
converting back to septic may not be easy (not impossible), your septic field might be filling in with roots ,like mine. (mine is uphill) some root killer in the tank with a ton of water might help. HTH