Sewage Backup Health Risks: Why It's a Biohazard

A sewage backup is unpleasant in any form: a toilet overflowing into a bathroom, a floor drain bubbling up in a basement, or a main line failure flooding a lower level. Beyond the smell and mess, sewage carries health risks that make it different from a clean water leak. This guide explains why, what to avoid, and how to protect your household.

Types of water damage

Restoration professionals often describe water by how contaminated it is:

• Clean water comes from a sanitary source, such as a broken supply line.
• Gray water has some contamination, such as water from a washing machine or dishwasher discharge.
• Blackwater is grossly contaminated, such as sewage, toilet backflow containing waste, or floodwater that has mixed with sewage.

Water can also become more contaminated over time. A clean water leak left standing for days can grow bacteria and become a more serious problem.

Health risks of sewage

Sewage can contain bacteria such as E. coli and Salmonella, viruses including norovirus and hepatitis A, and parasites. CDC's floodwater guidance notes that eating or drinking anything contaminated by sewage-laden water can cause diarrheal disease, that open wounds exposed to it can become infected, and that skin rashes and other illnesses are possible. CDC advises staying out of contaminated water when possible, washing with soap and clean water after contact, and washing contaminated clothing in hot water with detergent.

Risk is higher for:

• Young children, who touch surfaces and put their hands in their mouths
• Older adults
• Pregnant people
• Anyone with a weakened immune system or open wounds
• Pets, which walk through contamination and then groom themselves

Why porous materials are usually removed

Sewage soaks into carpet, pad, drywall, insulation, upholstered furniture, mattresses, particleboard cabinets and cardboard. These materials are difficult or impossible to disinfect all the way through. Industry practice is generally to remove porous materials that sewage has soaked, then clean and disinfect the structure. Hard, non-porous items such as metal, glass and sealed tile can usually be cleaned and disinfected. Leaving soaked porous materials in place also invites mold growth.

What not to do

• Do not wade through sewage, especially with cuts or open wounds.
• Do not let children or pets into the affected area.
• Do not use household vacuums or carpet cleaners on sewage.
• Do not keep using toilets, sinks, showers or appliances that drain into a backed-up line until the plumbing problem is fixed.
• Do not turn on electrical equipment or touch outlets in standing water. If water is near electrical panels or outlets, keep away and contact your utility or an electrician.
• Do not use contaminated water for anything. CDC advises against using possibly contaminated water for drinking, cooking, brushing teeth, washing hands or making baby formula.
• Do not mix cleaning chemicals; some combinations produce harmful gases.

What you can do right away

1. Stop the source if you safely can. Stop running water and flushing. If the backup comes from the public sewer, call your local sewer utility. If it is your own line, call a plumber.
2. Keep people and pets out.
3. Ventilate by opening windows if it is safe to do so.
4. Turn off HVAC if it draws air from the affected area.
5. Take photos from a safe spot for insurance.
6. Call your insurer. Many homeowners policies need a specific endorsement to cover sewer or water backup. Ask what your policy covers.
7. Call a professional for cleanup.
8. Wash your hands and any skin that contacted sewage with soap and clean water.

What professional sewage cleanup involves

• Removing standing water and solids
• Removing contaminated porous materials, often including drywall cut to a level above the water line
• Cleaning and disinfecting structural surfaces and hard contents
• Drying the structure to prevent mold
• Packaging and disposing of contaminated materials
• Documenting the work for insurance

Plumbing repairs are separate and should be done so the backup does not recur.

Septic systems and wells

Homes on septic systems and private wells have additional concerns. CDC publishes guidance for septic and onsite wastewater systems after flooding. If a septic system has backed up or flooded, have it inspected before resuming normal use. If a private well may have been contaminated, have the water tested before drinking it.

Documenting for insurance

Insurers will usually want to know the cause of the backup, the date it happened, and what was damaged. Keep the plumber's or sewer utility's report on the cause, photos taken before cleanup, the cleanup company's written scope and invoice, and a list of damaged contents. If the backup came from a municipal line, ask the utility how to report it; some have their own claim processes. See our guide on insurance documentation.

Rental and commercial properties

In rentals, sewage backups affecting units are generally the landlord's responsibility to repair, and tenants should notify the landlord promptly in writing. In multi-unit buildings, a backup in one unit may come from a shared line, and other units may be affected. Businesses, especially those serving food, should check with their local health department about any requirements before reopening affected areas.

Health after a backup

If anyone develops vomiting, diarrhea, fever, a wound that becomes red, swollen or oozing, or other symptoms after contact with sewage, contact a health care provider and mention the exposure. CDC advises seeking care promptly for wounds that show signs of infection.

When to call a professional

Call a professional for any backup involving toilet waste or sewage, any backup that reached carpet, drywall or furniture, and any backup larger than a small, contained spill on a hard floor. To discuss a situation, contact New Dawn Bio Restoration or call 615-914-0790, and please confirm availability for your location.

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