Which of the following is NOT a common cause of sewer blockages?

Excessive rainfall is not typically considered a common cause of sewer blockages. While heavy rainfall can contribute to combined sewer overflows or cause temporary surges in flow, it does not usually directly obstruct the sewer lines. Blockages are more commonly attributed to solid materials accumulating within the pipes.

Sediment buildup, tree root intrusion, and grease accumulation are frequent culprits of sewer blockages. Sediment can collect in sewage pipes over time, creating blockages. Tree roots can invade and obstruct pipes, and grease, when poured down drains, can solidify and create significant clogs, making these issues critical factors in maintaining clear wastewater systems.