A sewage backup is nobody’s idea of a good time. The smell, the damage, the cleanup — it’s all a headache. But what’s lurking after the mess is even more worrying. According to new research, homes hit by sewage overflows can harbor dangerous bacteria, some even resistant to antibiotics, and that’s a health risk most people don’t realize. With aging pipes and more flooding from extreme weather, sewage backups are becoming more common, and so is the threat they pose inside our homes.The study, unveiled at the ASM Microbe 2026 conference, found almost half the Maryland homes checked after sewage backups had Enterococcus bacteria, and over one in ten had strains tough enough to ignore several common antibiotics. The research doesn’t prove everyone exposed gets sick, but it’s a warning call about the hidden health issues that come with these unlucky home disasters.
What did the study find?
Scientists at the University of Maryland (UMD) and the School of Public Health took 107 samples from 86 Maryland homes that had sewage overflows between October 2023 and June 2025. They searched specifically for Enterococcus, a family of bacteria that live in human and animal guts. So, finding them outside the body means there’s been fecal contamination, likely from untreated wastewater.Their findings were pretty alarming:Almost half (46%) of the homes had Enterococcus bacteria somewhere inside. Among those, 21% had E. faecalis and 27% had E. faecium — the two types known to cause nasty hospital infections, especially for people with weaker immune systems.Here’s the kicker: Over a third of contaminated homes had antibiotic-resistant Enterococcus, including 12% with multidrug-resistant (MDR) strains (bacteria that can shrug off three or more types of antibiotics). That’s the kind of bug doctors dread.
Why should we be worried?
It’s true that most Enterococcus bacteria don’t cause problems. They hang out in your gut, minding their own business. But if E. faecalis or E. faecium end up somewhere else in the body, they can trigger urinary tract infections, wound infections, blood infections, or even infect your heart. The real challenge comes when bacteria survive the usual antibiotics. These tough strains are harder (and more expensive) to treat, and sometimes we run out of effective drugs.
Why could this problem become more common?
The timing of this study matters a great deal. One trend that has stood out is how homes that had a sewage overflow or water event in the past month were much more likely to have Enterococcus (and the drug-resistant kind) on surfaces than homes where the incident happened longer ago.Numbers were small, so the researchers want bigger studies to confirm this, but it looks like the highest risk for exposure is soon after the backup, while germs are still lingering.
Why is this problem getting worse?
The answer is simple: the pipes running under our cities are old, and major storms happen more often. When sewers can’t handle the load, backups push untreated wastewater into basements, bathrooms, whatever’s closest to the overwhelmed system.With more extreme weather and stressed-out infrastructure, more homes end up dealing with sewage and with germs that stick around long after the water’s been mopped up. In fact, earlier research from the same university showed bacteria can linger in a home for months after a sewage spill. That’s why just scrubbing the surface usually isn’t enough.
How do you protect yourself?
The first rule: avoid direct contact and breathing air near the mess, since sewage can carry everything from bacteria to viruses.Thereafter, if you have a sewage backup:
- Wear waterproof gloves, boots, and, if you can, an N95 mask when you need to be in the mess
- Keep kids, older adults, pregnant people, and those with weak immune systems away until everything’s clean
- Toss carpets, mattresses, insulation, and upholstered furniture that got soaked—you can’t disinfect them properly
- Scrub all hard surfaces with a strong disinfectant
- Wash your hands thoroughly when you’re done
- For big messes that seep into walls or floors, call remediation pros
Despite the precautions, if you end up getting sick and notice signs like persistent diarrhea, vomiting, fever, skin infections, or weird wounds, consult with a professional healthcare provider, especially if you have health problems that make fighting infections harder.
What’s next?
The Maryland team plans to keep studying more homes, hoping to understand just how long bacteria stick around after a backup or a flood. They also want to help local communities learn how to lower the health risks when sewage hits the basement.While the research is still awaiting peer review, it paints a sobering picture: after a sewage backup, the dangers don’t leave with the water. A quick, thorough professional cleanup using the right protection can safeguard both your home and your health from germs increasingly hard to kill with antibiotics.
