Rainy Season Plumbing Checklist for Los Angeles Homes
Los Angeles goes months without real rain, and then a storm rolls in. That's when plumbing problems tend to show up: drains that were fine all summer back up, yard drains overflow, and older sewer lines that have been quietly collecting roots and debris get tested all at once. A little preparation before the first big storm costs far less than cleaning up after a backup.
This year makes it more important. NOAA's Climate Prediction Center has an El Niño Advisory in effect and expects a strong-to-very-strong El Niño through the winter of 2026–27, the kind of "super El Niño" that can bring a wetter-than-normal winter to Southern California. That makes clear drains, an accessible cleanout, and a healthy sewer line your best protection before the storms arrive.
The 5-minute version 1. Clear gutters, downspouts, and yard drains. 2. Find your sewer cleanout and keep it accessible. 3. Don't ignore slow or gurgling drains. 4. Get a slow line cleaned before the storm. 5. Test your sump pump if you have one.
1. Clear the water paths around your house
Rain has to go somewhere that isn't your foundation, garage, or sewer line. Walk the property and check:
Gutters and downspouts: clear leaves and debris so water leaves the roof and drains away from the house.
Yard and patio drains: pull out debris and run a hose to confirm water drains freely.
Grading near the foundation: water should slope away from walls, not toward them.
Rain from roofs and yards should never be tied into the sewer line. If a downspout or yard drain is connected to the sewer by mistake, heavy rain can overload it. If you're not sure where yours goes, a plumber can trace it.
2. Know where your sewer cleanout is
The cleanout is the capped pipe, usually outside near the house or the property line, that gives access to your main sewer line. In an emergency, a plumber can reach the line quickly if the cap is findable and not buried under plants, dirt, or storage. Take a few minutes now to locate it and clear the area around it.
3. Watch for early warning signs
Problems rarely arrive without notice. Pay attention to:
Slow drains in more than one fixture.
Gurgling from a toilet or drain when another fixture runs.
Sewer odors indoors or near the cleanout.
Backups in the lowest drain in the house, such as a floor drain, shower, or tub on the ground level.
When several fixtures act up together, the cause is usually the main line rather than a single fixture. Tree roots and built-up grease and debris are common culprits, and they get worse when heavy rain adds flow.
4. Get a clogged or slow line cleaned before the storm
If your drains have been slow, don't wait for the rain to find out how bad it is. Professional drain cleaning or sewer cleaning clears the blockage. For stubborn buildup, hydro jetting uses high-pressure water to scour the inside of the pipe. If a line keeps clogging, or is cracked or collapsed, it may need sewer line repair or replacement instead of repeated cleanings.
5. Test your sump pump, if you have one
Sump pumps are less common in Los Angeles than in wetter climates, but some homes with basements, below-grade garages, or low spots have one. A pump that sat unused all summer is worth testing before you need it:
Pour a bucket of water into the pit.
Confirm the pump turns on, empties the water, and shuts off.
Make sure the discharge line is clear and the pump is plugged into a working outlet.
If a drain backs up during a storm Stop using water in the house: no toilets, showers, laundry, or dishwasher. Keep kids and pets away from standing water. Sewage backups can carry bacteria. Skip chemical drain cleaners. They rarely fix a main line problem and can be hazardous to the people who have to work on it. Call a licensed plumber right away. Photos of the damage can help with an insurance claim.
Want your drains checked before the rain?
Boss Plumbing provides plumbing and heating service across Los Angeles. Call us at (323) 464-4700 or contact us online.
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