Regular repair and pumping of the sewer system will keep the sewer in good shape.
If you have to deal with a lot of tenants, it can put a pretty big strain on the sewer system.
My wife and I own a condo building that has 24 units. Eight of the units have three bedrooms, 12 of the units have two bedrooms, and the other four units are one bedroom rentals. The entire top floor of the building is for the repair supervisor who also acts as the management. The repair supervisor contacted me last week, because there was a problem with the sewage. He contacted a local plumbing business and found out that our tank was nearly full. The toilets were starting to back up and the drainage was slow. We got the tank pumped, but it was filled back up the next month. With all 24 units filled, the sewer needs to be pumped monthly now. I am unhappy about the circumstances, because it costs a lot of money to have a septic and pumping business come to the property. Unluckily, the only thing I can do other than that is to substitute the septic tank and buy something that is twice as big. I have to put out a big amount of money up front or a little bit of money over time. Either way I have to spend more money on the septic and I have no idea where that money is going to come from. I’m barely making enough to cover the costs of the building and staff.