What I had cleaned out was the secondary drain (seldom used except by the humidifier) that ran to the outside & connected to the sewer. The other drain (for bathroom, kitchen & laundry) is separate. There may be some blockages between the drain tiles that go around the house, but I'd have to dig up the whole foundation to get to them. But they seem to be working well enough, so I shouldn't have to do that. At least I think I explained that right.