Sewage Odor Removal in Roseville, MI

Why does the house still smell after the sewage is gone?

Smell is chemistry. Sewage releases compounds that your nose picks up at tiny concentrations, and those compounds soak into any material that can hold them. Carpet and pad, drywall paper, wood framing, insulation, upholstery, boxes and even unsealed concrete absorb odor-causing material along with the liquid. After the water is pumped away, those materials slowly release the smell back into the air.

That is why a basement can look clean and still smell. The visible surface has been dealt with, but something porous nearby is still full. Spraying fragrance over it hides the smell for a day. Removing or treating the source is what makes it go.

This page is about odor. The earlier stages are covered elsewhere: the disinfection page explains cleaning and treating surfaces, and the drying page covers the moisture side. Often a smell that will not leave is a sign that one of those stages was incomplete.

Where does a sewage smell hide?

Look for the places where liquid could go and stay.

What actually removes the odor?

The honest list is shorter than the marketing makes it seem.

1. Remove the source

   Porous materials that held sewage, such as pad, saturated drywall and insulation, have to go. This is the most effective single step.

2. Clean thoroughly

   Residue on hard surfaces is the odor source. Washing with a cleaner removes it, and disinfecting without cleaning does not.

3. Dry the structure

   Damp materials keep releasing odor. Drying to target stops it and prevents a musty smell from replacing the sewage smell.

4. Treat what remains

   Sealers and odor-neutralizing products are applied to surfaces such as concrete and framing, once they are clean and dry.

5. Clean the air

   HEPA air scrubbers with activated carbon filtration capture particles and many odor compounds while work is under way and after.

6. Verify

   Check the smell at the start of the day and after the house has been closed, not just while fans are running.

Are ozone machines, fogging and hydroxyl units worth it?

These tools show up in almost every odor conversation, so it is worth being plain about what they do and where they cause trouble.

Ozone generators produce ozone gas that reacts with odor molecules. Ozone is also a lung irritant, and the U.S. EPA warns that it can be harmful to breathe and that it can damage materials such as rubber. Use requires an empty building, with people, pets and plants out, and proper airing afterward. It is a finishing tool for some losses and not a first resort, and ozone does not remove the source.

Thermal fogging disperses a deodorizing agent as a vapor so that it reaches crevices. It can help, but it masks if used alone and the product matters, so ask what is being used.

Hydroxyl generators produce hydroxyl radicals that react with odors and can be used while a building is occupied, depending on the model. Results vary with the source and the setting.

Air scrubbers with carbon capture many odor compounds and particles, and they are common in professional jobs.

If a provider proposes one of these as the entire plan, with no removal and no cleaning, that is a sign to ask more questions. None of them replaces taking out what holds the smell. The mold prevention page explains why moisture left behind can make a musty odor that no machine solves.

How is the smell different from mold or a dry-trap problem?

Not every bad smell in a house after a sewage event is the sewage itself. Three causes get confused.

• Residual sewage: a sharp, foul smell that is strongest near the affected area and drains. It usually points to materials still holding contamination.
• Mold or mildew: a musty, earthy smell that tends to grow over days in damp, closed areas. It points to moisture left behind.
• Sewer gas from a dry trap: a smell that comes from a drain that has not had water in it for a while, because the water seal in the trap evaporated. Running water into the drain for a minute can restore the seal, and a plumber can check the vent system if it recurs.

Figuring out which one you have matters, since each one has a different fix. A plumber is the right person for a recurring sewer-gas smell, and a provider is the right person for the rest.

How do you know the smell is really gone?

Do the smell test the right way. Close the room for several hours, open the door in the morning and breathe in before any fan has run. Check on a humid day too, since moisture brings odor back. Smell near baseboards, near the drain and inside closets.

If a trace comes back, do not accept that it is "just the house settling". Odor returning after a week usually means something is still wet or still contaminated, and the provider should find it. Ask about moisture readings from the drying stage, because a smell that returns often tracks the humidity.

What about odor in a house that has an older foundation?

Older Roseville housing includes concrete block basements and poured walls that are porous and sometimes unsealed. These absorb liquid and hold smell. If the walls were wet with sewage, cleaning and sealing may be needed, and the process takes longer than on newer construction. That is a place where a patient provider is better than a fast one.

Tell the provider how old the house is and what the basement floor and walls are made of. That information changes the plan.

What if the smell is in the air ducts or the furnace?

If the furnace, air handler or return grille sat in the affected area, the heating and cooling system can circulate the smell. A smell that is strongest at supply registers, or one that appears in rooms nowhere near the basement, points in this direction. The first step is to turn the system off if a provider advises it during active cleanup, and to have the return area cleaned and the filter replaced.

Duct cleaning is a larger decision. Ducts that did not take on liquid generally do not need to be opened, and cleaning them without cause is a sale and not a fix. If sewage reached the ducts, or if the return pulled contaminated air, a provider or an HVAC technician can evaluate the system. Ask what they found before agreeing to any duct work.

What do you do with fabrics, boxes and belongings that smell?

Contents hold odor long after the room is clean. Clothes that were stored in the affected area can often be washed, usually separately and on a hot setting that the fabric allows. Plastic bins, glass and metal can be cleaned and treated. Cardboard, paper, books and upholstered pieces that absorbed odor are usually not worth saving, because there is nothing to wash and the smell goes with them.

For sentimental items, a specialist may be able to help, and the provider can say whether it is realistic. Photograph valuable items before discarding them and list them for your insurer. The carpet page covers area rugs and what can be cleaned on the floor.

What can you do on your own to help?

• Keep the area ventilated if the provider says it is safe, but do not open windows on humid days if the dehumidifiers are running.
• Do not spray air fresheners or scented candles as a fix. They mask a smell and they make it harder to judge progress.
• Wash fabrics that were not in the water separately, because they pick up smell from a contaminated room.
• Run a household dehumidifier after the professional drying, and keep humidity in the range the EPA recommends for indoor air, roughly 30 to 50 percent.
• Report any smell that returns, and do it early.

A provider in our network can look at the house and tell you what is holding the smell. If the smell has outlasted the cleanup, our call line can connect you to one.

Questions people ask

Related help