Blocked Sewer Drain
If your main sewer line blocks up, this can cause some or all of the other fixtures being blocked as well.
It may be blocked in the inspection shaft (which is the point to which the drain runs, normally located out the very front or back of the property). The inspection shaft should be visible some are buried and difficult to locate.
The most common cause of a blockage in the main drain is tree roots which enter through cracked or damaged pipes underground. This cannot be cleared properly with a plunger and would require either an electric eel/roto rooter or to use a high pressure jetter.
We can then inspect the drain with a CCTV drain camera to ensure the entire amount of roots has been cleaned properly and to ensure no other blockages exist.