What are the signs that my main sewer line is clogged?

Warning signs can include several drains becoming slow at once, gurgling toilets, recurring backups, or wastewater appearing at a low floor drain, tub or shower. Problems involving several fixtures suggest a shared drainage problem, but symptoms alone cannot locate a blockage or prove the public sewer main is at fault. A single slow fixture may have a local clog; septic-system failure can produce similar symptoms. Stop adding water if wastewater is backing up. Contact a qualified plumber and your sewer utility, or a septic professional where applicable, to determine the cause and whether a camera inspection or other investigation is appropriate.