Rain and sewers
Rainy Season Sewer Backups in Los Angeles
Short answer: heavy rain can add water to older sewer lines through cracks and joints, and roots and buildup in the line make a backup more likely. If sewage is coming up, stop using water, and find out whether the blockage is on your side or the city’s.
If a backup starts in the rain
- Stop using water in the house
- Do not flush or run the washer
- Check whether neighbors are affected
- Call the city if the main looks blocked
Take photos of the backup for your records.
Why rain can lead to backups
Los Angeles has long dry spells, so sewer lines are often not tested until a heavy storm arrives. Then several things can happen at once.
- Extra water in the line: rain can seep into older pipes through cracks and loose joints.
- Roots and buildup: a line that was partly blocked on a dry day cannot handle the extra flow.
- Debris: storm runoff can carry leaves and dirt toward drains and openings.
Specific causes vary by neighborhood and by line. A camera shows what is happening in yours.
Last updated October 2026.
Is it your pipe or the city’s
If sewage is coming up in the street or in several homes on the block, the public main is the likely problem. In the City of Los Angeles that is maintained by LA Sanitation. If only your home is affected, the problem is probably in your private line.
Details in who is responsible for the sewer line and who to call by city.
What to do during a backup
- Stop running water and do not flush.
- Keep kids and pets away from any overflow.
- Take photos for your records.
- Call the city if the main looks blocked, or call a plumber if it is your line.
See emergency sewer backup for the full list.
How to get ready before the storm
- Find your cleanout so the plumber can get in fast.
- Have the line filmed if it has backed up before.
- Clear leaves and debris from outdoor drains and gutters.
- Remove roots and buildup in a line you already know is weak.
Signs your line may struggle in a storm
- A past backup after rain.
- Slow drains on dry days.
- Large trees near the sewer line.
- An older house with clay or fiber pipe.
- A cleanout you have never opened.
These are reasons to have the line cleaned and checked on camera before the rainy season. See sewer camera inspection.
After the storm: what to do next
- Stay out of any area with sewage on the floor until it is cleaned.
- Wear gloves and boots and wash well after contact.
- Take photos and notes of the backup, time and affected rooms.
- Have a plumber clear and camera the line to find the cause.
- Ask a cleanup company to handle affected flooring and walls.
Water and sewage damage is a separate job from clearing the pipe.
Keep a simple record
A short log helps if you need to report a problem or talk to the city. Note the date, what drains were affected, whether neighbors had problems and what the plumber found. Keep the footage if a camera was used. See LASAN sewer lateral rebate if your line needs a repair.
Common questions
Does rain cause every sewer backup?
No. Many backups are plain clogs. Rain adds load and makes a weak line show up.
Who pays for the cleanup?
It depends on where the problem was and the details of your situation. Ask the city and your plumber, and keep your photos.
Can hydro jetting prevent a rainy-season backup?
It removes buildup and roots that cause trouble. It cannot fix a cracked pipe that lets water in.
Backup during a storm?
Call and tell us what you are seeing, and a local plumber will talk you through the next step.