Blocked Toilet vs Blocked Main – How to Tell

Typical signs

• Local toilet only: water rises just in that toilet when flushed, other fixtures work fine
• Main drain blockage: multiple fixtures slow or backing up, gurgling in sinks, outdoor gullies overflowing

Quick diagnostic checks

• Test other fixtures: run sinks, baths, showers nearby—do they drain normally?
• Look at outside chambers: if safe, lift the nearest inspection cover—is it full or empty?
• Listen for gurgling: flushing causes bubbling in other drains = main issue
• Check multiple toilets: if you have more than one, does flushing affect others?

What the evidence tells you

• Chamber empty + toilet won't clear: blockage is between toilet and chamber (local)
• Chamber full + multiple fixtures affected: blockage is downstream of chamber (main drain)
• Only one fixture affected: almost always local
• Outdoor gullies overflowing: definitely a main drain issue

Next steps

• Local toilet blockage: plunge or rod carefully; if persistent, may need professional auger
• Main drain issue: CCTV survey to locate and identify blockage type
• Unsure or unsafe: call a professional—don't risk flooding or injury

For recurring blockages, a survey can reveal underlying problems like root ingress, collapsed sections, or grease buildup.