Start with what you can see
Useful details include where water is backing up, whether more than one fixture is affected, when the issue started and whether wastewater is overflowing. These clues help frame the enquiry; they are not a remote diagnosis.
- Stop using affected fixtures if water is overflowing.
- Keep people and pets away from wastewater.
- Share any known access points or previous work.
- Do not mix chemical drain cleaners.
What may happen next
Drain clearance can involve different methods. High-pressure water jetting or a CCTV survey may be relevant in some cases, but suitability depends on the pipework, access and the cause of the problem.
Read about water jetting or see when a camera survey may help.