Modern toilet paper is a paradox. It must be strong enough to survive wiping but weak enough to disintegrate in water. This balance is achieved through:
Tree roots seek water and nitrogen (found in waste). They enter via microscopic pipe cracks. Roots are hairy; TP is fibrous. The root hairs snag the paper. Over time, the root mass + TP creates a "root ball filter" that stops 100% of solids while allowing only water to pass. The outside drain then fills with paper. outside drain blocked with toilet paper
Modern low-flow toilets are excellent for conservation, but sometimes they do not provide enough water volume to push toilet paper all the way to the main sewer. The paper settles in the pipe or the drain inspection chamber, creating a partial blockage that grows over time. Modern toilet paper is a paradox