How to Get Rid of Sewer Smell in Your House: 6 Places You Need to Check

Table of Content

1. Bathroom: Check Your Toilet and Shower Area

The bathroom is the first place most people suspect and for good reason. Sewer smells often start here, but the toilet isn’t always the only source.

Toilet Wax Ring Issues

Underneath your toilet, there’s a wax ring that seals the base to the drain pipe. If that ring is cracked, dried out, or loose, sewer gas can escape right into your bathroom.

How to tell:

• The toilet wobbles
• You see water pooling at the base
• The smell gets worse after flushing

How to fix it:

• Replace the wax ring (a DIY job if you’re handy)
• If unsure, call a professional to reinstall the toilet securely

Read also – Why Toilet Leaking Around Its Base?

Cracked Base or Loose Seals

Water can leak from cracked toilet bowls or loose floor seals, especially if the toilet shifts with use. Moisture build-up under the toilet can cause mold and sewer odor.

Fix:

• Remove old caulk around the toilet base
• Clean the area thoroughly
• Apply a fresh bead of waterproof caulk around the seal

Dry Shower P-Trap

If you haven’t used your shower in a while like in a guest bathroom or after returning from a trip the P-trap may have dried out. This U-shaped pipe is meant to hold water to block sewer gas from rising back into the home.

Fix:

• Run the shower for a minute to refill the trap
• Add a few drops of mineral oil to slow evaporation

Shower Drain Biofilm

If you use soaps, shampoos, or body washes, they can mix with hair and skin cells in your drain and form a layer of bacteria called biofilm. This can trap odors and mimic the smell of sewer gas.

How to clean it:

• Remove the drain cover
• Pour hot water (150°F max) down the drain
• Add 1 cup white vinegar + ½ cup baking soda
• Wait 2 hours
• Pour another gallon of hot water and scrub with a drain brush

Read more about: Home Remedies For A Clogged Drain

2. Bathroom Sink: Don’t Forget the Overflow Hole

Many sinks have a small overflow hole just beneath the faucet. This area often traps soap scum, hair, and bacteria leading to a surprisingly strong sewer-like smell.

How to clean it:

• Use a small bottle brush dipped in vinegar to scrub it out
• Or pour a 50/50 mix of bleach and water down the overflow hole
• Rinse with hot water

Also check the P-trap under the sink it may be dry or partially clogged.

 

3. Kitchen Sink: Focus on the Garbage Disposal

Your kitchen sink deals with food scraps, grease, and all sorts of liquids. If you have a garbage disposal, the splash guard (that black rubber ring at the top) can trap bits of food and start to smell.

How to Clean the Disposal and Splash Guard

Kitchen Sink

Method 1: Manual Cleaning

• Turn off the disposal
• Flip the splash guard inside out carefully
• Scrub the underside with a brush and dish soap

Method 2: Deodorizing Rinse

• Pour ¼ cup baking soda down the drain
• Wait 10 minutes
• Add 1 cup vinegar
• Let it foam and sit
• Finish with hot water and run the disposal

Bonus Tip: Toss lemon or orange peels into the disposal for a fresh scent.

 

4. Laundry Room: Washing Machine and Floor Drains

You might not think of your washing machine as a source of sewer odor but it’s connected to your drain system, and things can go wrong.

Washing Machine Drain Odor

Sometimes, smells come from the drain pipe behind your washer or the washer itself.

Fixes to try:

• Run a hot cycle with no clothes + ½ cup baking soda + ½ cup vinegar
• Or run a hot cycle with 1 cup bleach
• Leave the washer door open after use to air it out

Floor Drain Near Washer

Most laundry rooms have a floor drain. If unused, the water in the P-trap can dry out, letting sewer gas rise into the room.

Fix:

• Pour 1 gallon of water into the drain
• Add 4 oz of mineral oil to slow evaporation

5. Basement or Utility Room: Look for Damaged Pipes

If you’ve checked all your fixtures and still smell sewage, your dr

ain lines themselves might be damaged or cracked especially if you live in an older home with cast iron pipes.

Signs of a Damaged Sewer Pipe

• Unexplained sewer smell near basement walls or floors
• Puddles or wet spots without a clear source
• Cracked or sagging foundation in extreme cases

This is not usually a DIY fix. You’ll need a camera inspection and potentially trenchless sewer repair, which is less invasive and faster than digging up your yard.

6. Roof: Clogged or Blocked Sewer Vent Pipe

Every home has a vent pipe that runs up through the roof. It equalizes air pressure and helps push sewer gase

s out. But if this vent gets blocked by leaves, debris, or even a bird’s nest the gases can get forced back into your home.

How to Check the Roof Vent

If you’re comfortable on a roof:

• Carefully check the vent pipe opening
• Remove any visible debris
• Use a plumbing snake if you suspect a clog deep inside

If not:

• Contact a licensed plumber who can clear it safely

FAQs

Your house smells like sewer gas because the safety seals in your plumbing system have been broken or blocked. Normally, a U-shaped pipe called a P-trap holds water to stop the gas from rising. If this water dries up, or if a pipe is cracked, or the vent pipe on your roof is clogged, the gas can leak right into your home. It’s important to fix this fast, as sewer gas contains harmful substances like hydrogen sulfide, and long-term exposure can cause headaches or nausea.

Start by running water in every sink and shower to refill any dry P-traps. Also, check the base of your toilet. If it wobbles or the smell gets worse when you flush, the wax seal underneath it is likely broken and needs to be replaced immediately. You can try cleaning out the overflow hole in your sink with a small brush and vinegar, as this area often traps smelly bacteria. If the issue is complex, New Flow Plumbing can fix or replace that broken toilet seal.

Yes, absolutely! A dry P-trap is one of the most common causes of sewer smell. If you have a sink or shower that hasn’t been used for a while (like in a guest room), the water in that U-shaped pipe will evaporate. When the water is gone, there is nothing blocking the sewer gas from entering your house. Just run the water for a minute to refill it, and you can add a few drops of mineral oil to slow future evaporation and make the seal last longer.

The most likely reason is trapped food, grease, and grime stuck in your garbage disposal or the rubber splash guard. Soap scum and fats can form a sticky “biofilm” that traps odors. To fix this, manually clean the underside of the splash guard (after turning the disposal off!) and run a mix of baking soda, vinegar, and hot water through the disposal to clear out the smelly build-up. Toss lemon or orange peels into the disposal for a fresh scent.

The smell could be coming from the floor drain near the machine if its P-trap has dried out. pour a gallon of water down it. Or, the smell could be from the washing machine itself. Run a hot, empty cycle with baking soda and vinegar or bleach to clear out bacteria and soap scum inside the machine, and always leave the washer door open after use to let it dry out. Make sure the washer’s drain hose is correctly placed and not tightly sealed into the standpipe.

Yes, cracked pipes are a serious source of sewer odors, especially in basements or utility rooms and often in older homes with cast iron pipes. If the smell is constant and you can’t find a source at a fixture, it means the main drain line is damaged. You might also notice wet spots or see mold near the walls. For a reliable diagnosis in the Van Nuys area, New Flow Plumbing uses advanced camera inspections to locate these hard-to-find cracks without tearing up your home.

If the sewer vent pipe on your roof gets blocked by leaves, debris, or a bird’s nest, the gases can’t escape outside. This creates negative pressure in the plumbing system. Instead of the gas going up and out, it forces the smelly sewer gas to push back down and leak into your house through the weakest point, like a dry P-trap or loose seal. New Flow Plumbing can safely access and clear blocked roof vents in Van Nuys, which requires special tools and safety precautions.

While the main gases are usually methane and carbon dioxide, the gas that smells like rotten eggs is hydrogen sulfide, which can be harmful. You should never ignore the smell. Long-term exposure to high levels can cause symptoms like headaches or nausea. It is important to fix the leak fast. If you are in the Van Nuys region, New Flow Plumbing can quickly find and repair the source to keep your home safe and the air clean.

If the P-trap is refilled but the smell returns fast, the water might be siphoning out due to poor air pressure in the drainage system, which points to a vent pipe issue. It could also be a major leak that is allowing the gas in, such as a severely broken drain line or a loose toilet seal. The best next step is to get a professional evaluation using a plumbing camera to find the hidden issue that is causing the gas to leak.

You should call a professional if the smell continues after you’ve checked all the simple things (like refilling P-traps or cleaning drains). A strong, lingering smell often points to a serious issue like a broken drain line, a deep clog you can’t reach, a bad toilet flange, or a problem with the vent system on the roof. New Flow Plumbing has the proper equipment to fix these major issues correctly and for the long term.