What Bacteria Grows in Standing Water Inside a Home?

If the standing water came from a sewage backup or floodwater, it is considered Category 3 or 'black water.' This water contains pathogens from human or animal waste. Fecal coliform bacteria like E. Coli and Salmonella are often present. These bacteria can cause severe gastrointestinal illness, fever, and other infections if you come into contact with the contaminated water or surfaces.

Even clean water that sits for more than 48 hours becomes contaminated. Microbes from the air, dust, or building materials start to colonize it. This process, called amplification, turns Category 1 water into Category 2 or 3. Warm, humid indoor conditions can significantly accelerate this bacterial growth.

Exposure to bacteria in standing water can cause a range of health problems. Skin contact may lead to rashes, infections, or infected wounds. Ingesting contaminated water, even accidentally, can cause vomiting, diarrhea, and abdominal cramps. For individuals with asthma or allergies, mold and bacteria can worsen respiratory symptoms and trigger asthma attacks.

More serious systemic infections are also possible, especially from bacteria like Pseudomonas aeruginosa, which can infect wounds. If you or a family member develops a fever, chills, persistent cough, or gastrointestinal symptoms after contact with flood water, see a doctor promptly. Always inform the medical professional about the potential water exposure.

• Gastrointestinal illness: Nausea, vomiting, diarrhea, stomach cramps.
• Skin infections: Rashes, redness, swelling, or pus from open wounds.
• Respiratory issues: Coughing, wheezing, shortness of breath from inhaled bacteria.
• Systemic infection: Fever, chills, body aches, and fatigue.
• Worsened allergies: Increased sneezing, congestion, or asthma attacks.
• Eye or ear infections: Redness, irritation, or discharge from contact.

Your safety is the first priority. Treat all standing water as potentially hazardous. Avoid contact if possible. If you must enter the area, wear rubber boots, gloves, and an N95 respirator mask. Turn off the electricity to the affected area at the breaker box if it is safe to do so. Do not use household fans, as they can aerosolize contaminants.

Ventilate the area by opening windows if outdoor air is drier. Move undamaged belongings to a dry area. Take pictures of the damage for your insurance records. Do not attempt to start major cleanup or use a standard wet-dry vacuum on contaminated water. Wait for qualified professionals to assess and handle the biohazard.