Why it matters which one you have
Every fixture in a house drains through its own short pipe into a larger shared line, and the shared lines meet in the main line that carries everything out. A blockage in a fixture's own pipe affects one fixture. A blockage in a shared line or the main line affects everything connected to it, and wastewater can come up at the lowest opening, which is usually a shower, tub or floor drain. The response is different: a single fixture can often wait a short time or be cleared at home, while a main line backup needs action straight away.
Symptoms side by side
| What you see | Single slow drain | Main line backup |
|---|---|---|
| How many fixtures are affected | One | Two or more, often at once |
| Gurgling | From that drain only | Toilets and drains gurgle when other fixtures run |
| Water coming up elsewhere | No | Yes, often in a tub, shower or floor drain |
| Smell | Usually a drain odor | A sewage smell is common |
| Washing machine drains | No effect | A tub or floor drain may fill |
| Urgency | Can often wait a short time | Urgent |
A safe five-minute check
This check tells you whether you are dealing with one fixture or the shared line. Do it with small amounts of water. Do not run large volumes, because water pushed into a blocked main line has to come out somewhere.
Stop heavy water use
Pause the washing machine, dishwasher and any showers.
Look at the lowest drain first
Check the lowest shower, tub or floor drain in the house. If it holds water or smells of sewage, treat it as a main line problem.
Run one small sink
Run a bathroom sink for a few seconds, on the other side of the house if you can. Watch other drains and listen for bubbling or gurgling in toilets and tubs.
Flush nothing
Do not flush a toilet to test the line. If the line is blocked, you will add water to a line that cannot take it.
Decide
If other fixtures gurgle, slow or show water, call about the main line. If only the one drain misbehaves, it is a local blockage.
What causes each one
A single slow drain
Hair in a tub, grease in a kitchen sink, soap scum in a bathroom basin, or debris in the trap. These sit close to the fixture and clear with basic cleaning.
A main line backup
- Tree roots that have entered through a crack or joint.
- Grease buildup along the pipe wall that finally closes the line.
- Wipes and flushed items that collect at a bend.
- A sag or offset joint that catches debris.
- A collapsed or crushed section that stops the flow.
What to do in the first hour of a main line backup
Stop all water use
No flushing, laundry, dishwasher or showers. Tell everyone in the house.
Keep people and pets away from sewage
Wastewater can carry bacteria. Avoid contact, and keep children and animals out of the area.
Locate your main cleanout
It is usually a capped pipe outside near the house or in a garage or basement. Knowing where it is speeds up the visit. Do not open the cap if water has backed up to it, because that can release sewage.
Protect what you can
Lift rugs and belongings off the floor near the affected drain. Open a window for ventilation.
Take photos and notes
Photos of the backup and a note of when it began help with the diagnosis and may be useful for insurance.
Call
Call (512) 729-9513 and describe which fixtures are affected, which drain showed water first, and how fast it is spreading.
Handling sewage safely
Sewage is a health hazard, so treat any contact seriously until the line is cleared.
- Wear waterproof gloves and boots if you must enter the area, and wash hands thoroughly afterward.
- Do not use shared household towels or sponges for cleanup.
- Hard, non-porous surfaces can be cleaned and disinfected once the backup is cleared. Porous materials that have soaked up sewage, such as carpet padding, are often discarded. Ask a cleanup professional about your situation.
- Check with your insurer about coverage for backups before starting cleanup.
After the line is cleared
Clearing the line stops the backup. It does not tell you why it happened. If the cause is roots, a sag, damage or heavy buildup, it can happen again. A camera look after clearing shows the condition of the line, so the next step rests on what is actually there. See our guide on when a sewer camera inspection is worthwhile.
Common mistakes
- Running water to see whether the drains have cleared.
- Pouring chemical cleaner into a backed-up main line.
- Opening the cleanout cap when it is full.
- Waiting overnight in the hope it clears on its own. A blocked main line rarely does.
- Treating a repeat main line backup as a one-off.
How to reduce the risk of a backup
- Flush only toilet paper, and keep wipes out of the toilet.
- Keep grease out of the kitchen drain.
- Keep large trees and shrubs away from the sewer line.
- Know where your cleanout is, and keep the area clear.
- If the main line has backed up before, schedule an inspection.
Frequently asked questions
Is a slow drain an emergency?
Why does my floor drain smell or fill when I run the washing machine?
Can I clear a main line blockage myself?
What if the backup happens at night?
Will my insurance cover a sewer backup?
How do I know if it is the city sewer or my line?
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Where we help
We take calls from Buda and nearby communities, including Kyle, Uhland, Manchaca, Creedmoor, San Marcos and more. See all service areas.