Some common causes of a blocked toilet include; 

• Flushing inappropriate items: Flushing items like wipes, paper towels, feminine products, ear swabs, and hair can result in clogs and ongoing plumbing problems. Even products that are marketed as “flushable” can cause issues as they do not degrade as easily as regular toilet paper. Your toilet is not a bin, and treating it as such can lead to blocked pipes.
• New low-flow toilets: Newer homes may have low-flow toilets, which sometimes lack the necessary pressure to push waste material through the drain effectively. This low flushing power and smaller throat can result in material not fully flushing, leading to a perpetually clogged toilet.
• Excessive use of toilet paper: Toilet paper is designed to degrade and flow through the drain without causing blockages. However, if too much is used, or if the toilet paper is thicker and multi-ply, it may not dissolve as well in water, leading to potential clogs.
• Clogged toilet trap: Your toilet has an S-shaped trap, similar to the P-trap found in your sink. The job of this trap is to catch objects and prevent them from clogging the drain line. However, if non-flushable items or excessive amounts of toilet paper are flushed, they can get stuck and stop the trap from functioning properly.
• Blocked toilet vent: Your toilet is connected to a vent that allows fresh air to enter the plumbing system, thereby increasing flushing pressure. If there’s a blockage in this vent, the pressure can drop, leading to recurring clogs. Symptoms of a blocked toilet vent can include gurgling noises, slow draining, and a foul sewer smell in your home.
• Waste and debris buildup: Over time, waste and debris can accumulate in your pipes, causing them to become blocked.
• Tree roots in the drainage system: Tree roots can invade your underground drainage system and cause blockages.
• Cracked or broken pipes: These can prevent waste and water from flowing smoothly, leading to clogs.
• Faulty flush valve seal: If the flush valve seal isn’t working correctly, it can result in weak flushes that don’t effectively remove waste from the toilet bowl.
• Old or unmaintained external pipes: If your external pipes are not maintained or are old and collapsing, they can lead to toilet blockages.
• Slow-moving or unmaintained septic systems: If your home has a septic system, any issues with it, such as slow movement of waste or lack of maintenance, can lead to toilet blockages.
• Hard water issues: Hard water, or water that has high mineral content, can cause buildup in your pipes and lead to blockages.