I've been having slow drain problems throughout my home. I know the drain problems are starting somewhere at the beginning of my main drain line going to the city utility line. Last night I removed my toilet and snaked 50 feet of line all the way out to the city's main. It didn't make any difference. I suspect I may have old clay pipes ('40s era) that are broken, thus the slow drain. Any advice or thoughts on how to handled this would be greatly appreciated. I have the sinking suspicion that I will need to replace my line the backyard. I suppose the other issue is that I don't have sufficient ventilation, but that hasn't been a problem in the past.