What are the common causes of a sewer line backup?

The most common causes of a sewer line backup are internal blockages, invading tree roots, and pipe defects that restrict flow. In homes, the usual trigger is non‑flushable items or grease buildup that slowly narrows the line until wastewater reverses. Backups are serious because contaminated water can carry bacteria and damage finishes; if sewage is coming up through drains, treat it as urgent. A single low spot in an older clay or cast‑iron line can act like a bowl that collects debris after every shower. We routinely handle these problems across the Denver metro, including Brighton. Colorado Cleanup Services provides 24/7 emergency sewage cleanup and sanitation.

Watch for these common culprits:

• Wipes, paper towels, and hygiene products that don’t break down
• Fats, oils, and grease that cool and harden inside the pipe
• Tree roots entering through small cracks and joints
• Heavy rain or municipal surges overwhelming aging or bellied laterals

Avoid using sinks and toilets, keep people and pets away from contaminated areas, and call a qualified team to inspect and start cleanup. <br/> Updated: 2026-04-13 <br/> Need help in Brighton, CO? Call (303) 237-4406 or book online.