You walk into the guest bathroom you haven’t used since summer, and there it is: that rotten-egg smell. Or it shows up in the kitchen after a big family dinner, or in the hallway every time it rains. A sewer smell in the house is one of the most common calls we get from Studio City, Sherman Oaks, Encino and the rest of the Valley, and it gets more common as the holidays get closer.
The good news is that a sewer smell usually has a findable cause, and some of those causes take two minutes to fix. Here’s how we track it down at Flood Brothers Plumbing, room by room, plus the signs that mean it’s time to call.
First, a quick safety note
Sewer gas smells bad because of hydrogen sulfide and other gases from the drain system. A faint, now-and-then whiff is mostly a comfort problem. A strong, constant smell is different: open windows, keep people and pets out of the room, and call a plumber. If you smell
natural gas (a sulfur or “skunk” smell near the stove, water heater or furnace), that is a different emergency. Leave the house and call the gas company first.
Why Valley homes get sewer smells
A lot of homes in Studio City and across the Valley were built from the 1940s through the 1970s. Many still have original cast iron or clay sewer lines, and plenty have been remodeled more than once. That mix leads to a few local patterns we see over and over:
- Older cast iron and clay lines that crack, separate at the joints, or let tree roots in. Big, mature trees are part of what makes Valley neighborhoods so nice, and their roots love old sewer lines.
- Remodels that skipped a vent. A new island sink or added bathroom without proper venting can pull water out of a trap and let sewer gas in.
- Raised foundations and crawl spaces on many hillside homes south of Ventura Boulevard, where a small drain leak under the house can smell long before anyone sees it.
- Rain. When storms load up the city system and the soil around your lateral, a weak spot in the line can push odor back toward the house. If your house only smells like sewer when it rains, that’s a strong clue.
Room-by-room: where the smell is coming from
The guest bathroom or a shower nobody uses
This is the number one cause, and the easiest fix. Every drain has a
P-trap, a curved section of pipe that holds a little water to block sewer gas. If a sink, shower or floor drain isn’t used for a few weeks, that water evaporates and the gas comes right up.
Try this: Run water in every sink, tub and shower for 30 seconds, and pour a bucket of water down any floor drain in the laundry room or garage. If the smell fades in an hour or two, you found it. Before guests arrive for the holidays, run the water in that guest bath once a week.
The toilet
If the smell is strongest right around the base of a toilet, the
wax ring under it may have failed. That ring seals the toilet to the drain. When it breaks down, or when the toilet rocks even a little, gas can escape. Signs include a toilet that wobbles, water around the base after flushing, or staining on the floor. This is a simple repair for a plumber, and it’s worth doing before it turns into a floor problem.
The kitchen
Kitchen smells are often grease and food buildup inside the drain, not sewer gas. Holiday cooking makes it worse: gravy, grease and potato peels are some of the most common causes of clogs we clear in November and December. If the smell comes with slow draining or gurgling, the line needs cleaning. Please skip harsh chemical drain cleaners. They rarely fix the real problem and can be hard on older pipes.
The laundry room
Washing machines drain fast and hard. If the standpipe is too short, has no trap, or the drain line is partly clogged, you can get gurgling and sewer smell every time the washer empties.
Every drain at once, or the whole house
If more than one fixture smells, or you hear gurgling in the tub when the toilet flushes, the problem is probably in the
main sewer line, not one drain. Roots, a sag (a “belly”) in the line, a crack, or buildup can all slow the main line and push odor back up. This is where a camera inspection earns its keep. Instead of guessing, we run a camera down the line and show you exactly what’s going on.
Outside the house or under it
A smell near the yard cleanout, along the side of the house, or coming up through the floor on a raised foundation can mean a broken or leaking line underground or in the crawl space. A
roof vent that is blocked (leaves, a bird nest) or cracked can also send gas back down into the house, especially on windy days.
When it’s time to call a plumber
Call us if:
- The smell keeps coming back after you’ve run water in every drain
- Several drains are slow or gurgling at the same time
- Water backs up into a tub or shower when you flush or run the washer
- The smell is strong, constant, or coming from under the house
- You notice wet spots, sinking soil, or extra-green patches in the yard over the sewer line
It helps to notice the pattern before you call: does it smell after rain, after the washer runs, or only in one room? That tells us where to start.
Gio’s $99 Special: snake and camera before the holidays
Through December 31, 2026, Flood Brothers is offering
Gio’s $99 Special: a sewer mainline snake plus a camera inspection for $99. Just mention
“Gio’s $99 special” when you call or text. It’s a smart move if you’re hosting this year, if your home has older sewer lines, or if you’ve noticed a smell or a slow drain and want to know what’s really going on.
Read more about Gio’s $99 Special.
If we find something on camera, we explain it in plain English and give you upfront pricing before any repair. When a line does need replacing, we offer
sewer repair and replacement, including one-day trenchless sewer replacement. If a backup has already made a mess, our
water damage team handles cleanup and odor treatment, and we work with insurance directly.
A family business that answers the phone
Flood Brothers Plumbing is family-owned and has been in business for more than 15 years. Owner Giovanni “Gio” Longo is a master plumber and a certified Flood Mitigation expert, and he runs the company the way he’d want his own family’s home treated. We’re licensed, bonded and insured (CA Lic #985487). Same-day service is guaranteed, a live person answers 24/7, and every job comes with our 100% satisfaction guarantee.
We serve homes across Studio City, Sherman Oaks, Encino, Woodland Hills and the rest of the Valley, plus Hollywood and the hills. Find your neighborhood:
Smell something you can’t place? Call or text
855-840-7800, day or night. Text us a photo of the drain if it’s easier. We’ll help you figure out whether it’s a two-minute fix or something that needs a camera, and we’ll never push you into a repair you don’t need.
Related reading: Rainy-season plumbing checklist for Studio City and Valley homes
