A toilet that backs up once is usually down to too much paper. A toilet that keeps doing it has an underlying problem, and it is not always in the toilet.
Toilet or drain? The quick test
Run the bath or a downstairs tap for a minute and watch the toilet.
- The water level in the toilet rises or bubbles: the blockage is almost certainly in the underground drain, downstream of the toilet. Water from the tap has nowhere to go but up the lowest fitting.
- Nothing happens in the toilet: the blockage is more likely to be in the toilet pan or the pipe directly behind it.
Also look at any outside inspection chambers. If they are full of water, the drain is blocked.
Common reasons a toilet keeps backing up
A partial blockage that never quite clears
Wipes, sanitary products and wads of paper can lodge in the outlet or soil pipe, leaving a small gap. Water trickles past, but anything solid catches, so the toilet works some of the time and backs up the rest.
Wipes
Many wipes, including some labelled flushable, do not break down quickly in drains. They collect at bends and combine with paper to form blockages.
Low-flush toilets
Modern toilets use less water per flush. That is good for water bills but means less force to carry waste along the drain, particularly on long, shallow runs. Using less paper per flush, or flushing twice, can help.
A blocked or damaged underground drain
If the toilet is the lowest fitting in the house, it is where a blocked drain shows itself first. Roots, displaced joints, a sagging section or a build-up of fat further down can all cause repeated backing up. Blocked drains explains more.
A blocked vent
The soil stack needs air to flow properly. A blocked vent (for example, a bird’s nest at the top of the stack) can cause gurgling and slow flushing.
A shared drain or sewer problem
If neighbours are affected too, the blockage may be in a shared drain or public sewer. See blocked sewers for how responsibility works.
What to do now
- Stop flushing until the problem is cleared.
- Try a proper toilet plunger if the blockage appears to be in the toilet itself.
- If water rises when other fittings are used, stop using water in the house and get the drain cleared.
Stopping it happening again
- Bin all wipes, cotton buds and sanitary products.
- Keep fat and food out of the kitchen sink, as it ends up in the same drain.
- If it keeps happening after the drain has been cleared, a CCTV drain survey will show whether there is a defect in the pipe.
For help in Southampton, see blocked toilets in Southampton or contact us.