Southern California is entering the 2026–2027 wet season with this year’s “Super El Niño” already present… and expected to strengthen.
El Niño is not one giant storm. It is a climate pattern that can increase the odds of wetter conditions and powerful storm systems in Southern California. It does not guarantee that every community will flood, but the current outlook is serious enough that homeowners, business owners, landlords, and property managers should prepare before the heaviest rain arrives.
From a plumbing standpoint, heavy rain often exposes a weakness that was already developing: a partially blocked sewer line, invasive tree roots, cracked underground piping, a neglected area drain, grease buildup, a failed sump pump, or an improperly maintained backwater valve.
At Western Rooter, we recommend addressing those warning signs now rather than discovering them during the middle of a storm.
The Most Important Plumbing Preparations to Make Now
Before the rainy season intensifies:
- Clear any drain that is already slow, noisy, or producing odors.
- Have recurring sewer problems inspected before heavy rain begins.
- Remove leaves, dirt, and debris from private area drains and catch basins.
- Test sump pumps and backup power systems.
- Locate and label the property’s main water shutoff.
- Check whether an existing backwater valve needs service.
- Create an emergency plan for occupants, employees, tenants, or customers.
- Save the number for a 24-hour emergency plumber before an emergency occurs.
Waiting until water or sewage is already entering the building limits the available options and can substantially increase the damage.
Plumbing Problems to Expect During Heavy El Niño Rain
Sewer Backups
A sewer backup is one of the most serious plumbing problems associated with prolonged heavy rain.
Water may enter damaged sewer laterals through cracks, separated joints, or root-damaged sections. Public sewer systems may also experience increased inflow during major storms. If the property’s sewer line is already partially restricted by roots, grease, scale, wipes, or other debris, the added pressure can push wastewater back through the lowest available drain.
Common warning signs include:
- Several fixtures draining slowly at the same time
- Gurgling toilets
- Water appearing in a shower or bathtub when another fixture is used
- Sewage odors
- Water collecting around an exterior sewer cleanout
- Recurring main-line clogs
These symptoms should be investigated before the storm. Professional drain cleaning and clearing may remove an obstruction, while a sewer camera inspection can help determine whether the line is cracked, collapsed, separated, or affected by roots.
Overflowing Exterior and Area Drains
Leaves, sediment, trash, landscaping material, and mud can block private area drains and catch basins. Once the drain’s capacity is reduced, water may collect around garages, loading areas, patios, stairwells, parking lots, or building entrances.
Clearing visible debris from the grate is useful, but it does not confirm that the underground line is open. A drain that handled light rain may still fail during a sustained downpour.
Root- or Grease-Affected Sewer Lines
Tree roots are a common problem in older Southern California sewer laterals. Roots enter through small defects and continue growing inside the pipe, where they collect paper and debris.
Restaurants, apartment buildings, hotels, and other high-use properties can also develop grease, sludge, and scale inside their drain lines. Depending on the pipe’s condition, professional hydro jetting may be recommended to scour buildup from the interior of the line.
Hydro jetting is not appropriate for every damaged or fragile pipe. Older systems may need a camera inspection before high-pressure cleaning is performed.
Sump Pump Failure
Properties with basements, below-grade rooms, elevator pits, low garages, or hillside drainage systems may depend on a sump pump.
The pump can fail because of:
- Loss of electrical power
- A stuck float switch
- A clogged intake
- A damaged discharge line
- An undersized pump
- Lack of maintenance
- No battery or generator backup
Test the system before the first major storm. Confirm that the pump activates, the discharge path is open, and water is carried away from the building rather than recirculated toward the foundation.
Leaks and Pipe Damage
Saturated or shifting soil can expose weaknesses in underground water and sewer piping. Storm debris can also damage exposed lines, while water entering utility rooms may affect water heaters, pumps, control panels, or other plumbing equipment.
Unexplained wet areas, reduced water pressure, running-water sounds, or a rapidly moving water meter may indicate a supply-line leak.
Which Properties Face the Greatest Plumbing Risk?
Older Homes
Homes with original clay, cast-iron, Orangeburg, or aging metal piping may have deteriorated joints, corrosion, root intrusion, low sections, or previous repairs that become vulnerable during wet conditions.
A history of recurring drain cleaning is itself a warning sign. Repeatedly clearing the same line without identifying the underlying cause may leave the property exposed to another backup.
Homes With Large or Mature Trees
Mature trees near the sewer route increase the likelihood of root intrusion, particularly when the pipe already has cracks or separated joints.
Low-Lying or Below-Grade Properties
Properties below the surrounding street, parking lot, or neighboring land may collect runoff more quickly. Basement fixtures, floor drains, showers, and low toilets are often the first places a backup appears.
Hillside Properties
Heavy rain can saturate and move soil around buried piping. Hillside properties should watch for erosion, exposed lines, new depressions, unusual wet spots, or changes in drainage patterns.
Apartment and Multifamily Buildings
A blockage in a shared main line can affect several units at once. Tenants may continue using water without realizing that activity in an upper unit is causing sewage to emerge from a lower fixture.
Property managers need a clear communication plan that tells residents when to stop flushing toilets, running showers, or using washing machines.
Restaurants and Food-Service Businesses
Grease, food waste, high fixture usage, floor drains, and strict sanitation requirements can make storm-related backups especially disruptive.
Preventive drain maintenance should be completed before peak rain periods, not after several fixtures have already stopped draining.
Retail, Industrial, and Warehouse Properties
These buildings often have large roofs, loading areas, parking lots, floor drains, catch basins, and equipment positioned near ground level. A blocked private drain or low entry point can quickly affect inventory, electrical equipment, machinery, and customer access.
Businesses should review their commercial plumbing systems as part of their broader storm-continuity plan.
How to Prepare Your Plumbing Before the Storm
1. Do Not Ignore Existing Warning Signs
A drain that is already slow will not improve when the weather gets worse.
Schedule service when you notice:
- Multiple slow drains
- Recurring toilet clogs
- Gurgling fixtures
- Sewage odors
- Water around a cleanout
- Frequent backups
- A sump pump that cycles irregularly
- Unexplained wet soil or low water pressure
The goal is to find and correct the restriction before the system is under additional stress.
2. Consider a Sewer Camera Inspection
A sewer camera can help locate roots, grease buildup, broken sections, offsets, low spots, or other defects without immediately excavating the property.
An inspection is especially useful when the property has experienced previous backups, repeated drain cleaning, mature trees, or older underground piping.
3. Clean Private Exterior Drains
Remove leaves, trash, soil, mulch, and other visible material from:
- Area drains
- Catch basins
- Patio drains
- Stairwell drains
- Parking-lot drains
- Loading-area drains
- Downspout outlets
Do not assume that a clean grate means the underground line is clear. Test drainage before the storm without creating artificial flooding or directing runoff toward neighboring property.
4. Test Sump Pumps
Pour enough clean water into the sump basin to activate the float. Verify that the pump starts, shuts off normally, and discharges water away from the structure.
Test any battery backup separately. Replace old batteries and keep access to the pump clear.
5. Locate Your Main Water Shutoff
Every adult occupant, property manager, and designated employee should know where the main shutoff is located and how to operate it.
Do not wait until a pipe has burst to search for the valve. Label it clearly and keep the surrounding area accessible.
6. Have a Backwater Valve Evaluated
A backwater valve is designed to reduce reverse flow from a sewer line into a building. It must be properly selected, installed, accessible, and maintained.
An old, stuck, obstructed, or incorrectly installed valve may not provide the expected protection. A plumber can determine whether the property has one and whether it is operating correctly.
7. Protect Plumbing Equipment in Low Areas
Inspect water heaters, recirculation pumps, treatment systems, controls, and other equipment located in basements, garages, pits, or low utility rooms.
Do not attempt to move, elevate, disconnect, or modify gas-fired or electrically powered equipment without a qualified professional.
8. Build a Business Emergency Plan
Commercial properties should document:
- The locations of water shutoffs and sewer cleanouts
- Who has authority to shut down water use
- Who will communicate with employees, tenants, or customers
- How after-hours access will be provided
- Which restrooms or areas should be closed first
- Where plumbing plans and maintenance records are stored
- Who will call the emergency plumber
- How operations will continue if restrooms or drains are unavailable
What to Do During a Storm-Related Plumbing Emergency
Sewage Is Backing Up
Stop using water throughout the affected property. Do not flush toilets, run faucets, start washing machines, or use dishwashers.
Keep people and pets away from the contaminated area. Sewage should be treated as a health hazard.
Do not remove a sewer cleanout cap when the line may be pressurized. Wastewater can discharge suddenly and cause injury or contamination.
Call a plumber immediately.
A Pipe Has Burst
Shut off the main water supply if the valve is accessible and it is safe to reach.
Turn off affected appliances only when doing so does not require entering standing water or approaching wet electrical equipment. Water near a breaker panel, outlet, appliance, or exposed wiring creates an electrical hazard.
Multiple Drains Begin Gurgling
Reduce water use immediately. Gurgling across several fixtures can indicate that air and wastewater are struggling to move through the main line.
Do not pour chemical drain cleaner into a backed-up system. It may not reach the obstruction and can create an additional chemical hazard for occupants and plumbing technicians.
Floodwater Enters the Building
Do not walk into standing water when electrical equipment, outlets, wiring, appliances, or utility lines may be involved.
Follow evacuation and utility instructions from local authorities. Plumbing damage can wait until the area is safe to enter.
What to Do After the Storm
Once the immediate danger has passed:
- Photograph visible damage before cleanup begins.
- Check low fixtures, floor drains, cleanouts, utility rooms, and crawlspaces.
- Watch for new odors, gurgling, slow drainage, low pressure, or unexplained wet areas.
- Restore water use gradually rather than running every fixture at once.
- Arrange a sewer inspection after any backup or repeated drainage problem.
- Use qualified cleanup professionals when sewage or contaminated floodwater entered the building.
- Remove or professionally remediate materials that cannot be safely cleaned and dried.
- Keep records of plumbing service, cleanup, repairs, and insurance communication.
A drain that begins working again after the rain may still contain roots, grease, debris, or structural damage. Temporary improvement does not necessarily mean the underlying problem has been corrected.
Frequently Asked Questions
Can heavy rain cause a sewer backup?
Yes. Heavy rain can contribute to sewer backups when a public system is under pressure or when a private sewer lateral has cracks, root intrusion, grease buildup, debris, or an existing partial blockage. Low fixtures are generally the first places wastewater appears.
What is the first thing I should do if sewage backs up?
Stop all water use, keep people and pets away, avoid contact with the wastewater, and call an emergency plumber. Do not continue flushing toilets or running water to “test” the line.
Should I use chemical drain cleaner during a storm?
No. Chemical drain cleaner is unlikely to correct a main sewer restriction and may create an additional hazard. A main-line backup requires proper diagnosis and mechanical cleaning, hydro jetting, repair, or another professional solution.
When should I call a plumber before the rain?
Call before the storm when several drains are slow, toilets gurgle, sewage odors are present, the main line repeatedly clogs, water appears near a cleanout, or a sump pump is unreliable.
Can a backwater valve prevent every sewer backup?
No device guarantees complete protection. A properly selected, installed, and maintained backwater valve can reduce the risk of reverse sewer flow, but it must match the property and remain accessible for inspection and cleaning.
What should business owners do first?
Identify the plumbing systems that could stop operations: shared restrooms, kitchen and grease lines, floor drains, sump pumps, sewer mains, water heaters, and low-lying equipment. Assign responsibility for shutting down water use and contacting emergency service.
Prepare Before the Heavy Rain Arrives
The best time to address a slow drain, recurring sewer problem, damaged line, or unreliable sump pump is before Southern California enters a prolonged period of heavy rain.
Western Rooter provides residential plumbing, commercial drain and sewer service, preventive maintenance, and 24-hour emergency response throughout Southern California.
For storm preparation or an active plumbing emergency, call Western Rooter at (626) 448-6455 or request our 24-hour emergency plumbing service.
