What Sewage Backups Can Mean for Home Health

The old farmhouse I grew up in had the common warning signs of an old onsite wastewater treatment system and aging plumbing: drains start moving slowly, laundry seems to overwhelm the system or wastewater backs up where it absolutely should not. For some families, this is a rare emergency. For others, it’s a problem they live with and manage by limiting water use, especially during storms, floods or when the house is full of guests.

Now, new research suggests these messy incidents may not be just unpleasant, but also bring harmful bacteria into the home.

Gathering facts

A recent study presented at ASM Microbe 2026 found that sewage backups can expose people to germs that may cause illness, including some that are resistant to antibiotics, which can make infections harder to treat. With heavier rain, more flooding and older sewer systems under strain, experts worry these events could become more common.

The concern stretches from big city sewer systems to individual OWTS. While people have long understood that sewage spills are a sanitation problem, there has been surprisingly little research on what happens inside homes after a backup. In this study, researchers collected 107 samples from 86 homes in Maryland over nearly two years, looking for bacteria linked to fecal contamination and testing how well different antibiotics worked against them.

What they found was concerning. Nearly half of the homes tested had Enterococci, a group of bacteria often used as a sign of sewage contamination. Some homes also had specific strains that can cause infections, especially in people with weakened immune systems. Homes that had recently experienced sewage or water intrusion were more likely to test positive, suggesting that the period right after a backup may be especially important for exposure.

The study also found antibiotic-resistant bacteria in more than one-third of the homes sampled. In more than 1 in 10 homes, the bacteria were resistant to several kinds of antibiotics at once. That matters because when bacteria are harder to treat, even routine infections can become more complicated. Homes with recent sewage or water intrusion appeared to have much higher levels of these tougher bacteria, though the researchers said the study was not large enough to be certain about every difference they saw.

Cleaning up

Taken together, the findings point to a bigger public health issue than many homeowners may realize. Sewage backups are inconvenient but more importantly, they may introduce hard-to-kill bacteria into the places where people live, play and recover when they are sick. As weather extremes increase and infrastructure continues to age, more households could face this risk.

That makes thorough cleanup especially important, particularly in homes with small children, older adults or anyone with a weakened immune system. The first priority is stopping more wastewater from entering the home. After that, cleanup should begin as quickly as possible. Here are the basic steps experts recommend:

• Keep children and pets out of the affected area until cleanup is complete.
• Wear rubber gloves and boots during cleanup
• Wash hands thoroughly after cleanup, and launder contaminated clothing separately
• Remove furniture, loose rugs and other movable items from the area.
• Remove wall-to-wall carpeting and padding, wrap  in plastic, and dispose at an appropriate transfer station or sanitary landfill. These  generally cannot be cleaned adequately.
• If carpeting is retained, hire a licensed carpet cleaning company to steam clean and disinfect it.
• Clean all hard surfaces — including linoleum, hardwood, concrete, wood trim and metal furniture — with hot water and a mild detergent, then rinse with a bleach solution made by mixing one tablespoon of liquid household bleach with one gallon of water. Allow surfaces to air dry.
• Have upholstered furniture, loose rugs and drapery professionally cleaned, or discard them if necessary. Inform the cleaning service of the sewage exposure.
• Remove and replace plaster, drywall and lath that have become saturated and are soft to the touch. If surfaces are only lightly wetted, clean them as you would other hard surfaces without oversaturating the material.
• Clean sinks, dishwashers and other plumbing fixtures affected by sewage backup with detergent, then rinse with a bleach solution.
• Disinfect mops, brooms, brushes and other cleanup tools using a bleach solution.
• Increase air circulation to reduce odors and limit mold growth by opening windows and doors; fans and heaters may help accelerate drying.

A sewage backup is not only a household nuisance, but can create real health risks, especially if cleanup is delayed or incomplete. Stress to your customers that good maintenance can lower the odds, but when a backup happens, treating it seriously and cleaning carefully can make a major difference for everyone in the home.