This happens without you even knowing how much your spending. Try and use the proper toilet paper for your toilet. Some toilets and sewer systems aren’t strong enough to push all the thicker toilet paper to the city sewer. If your debris you put down your toilet doesn’t make it to the city sewer you’ll have more clogged drains more frequently. Ask yourself do you really want clogged drains?
Also, make sure you clean out your sewer system yearly to the city sewer line. Besides tree roots that grow in our sewer drain line, there is much more that accumulates in your sewer line and hardens. If you have a low dipped lie this is also a reason to properly clean your sewer system yearly.