Why is floodwater in a basement treated as Category 3?
Floodwater carries soil, sewage, fuel and bacteria from streets, yards and drains, so it is classed as Category 3, the most contaminated category. Anything that comes up a floor drain from a combined sewer counts too. Porous materials it touches are removed rather than cleaned, and workers wear protective equipment.
The industry classifies water by how contaminated it is. Category 1 is clean, such as a broken supply line. Category 2 is gray water, such as washing machine discharge. Category 3 is black water: sewage, toilet backflow, and rising floodwater from rivers and creeks. Surface water from a storm joins that third group because it has crossed roads, lawns and drains before reaching the house, and in Dearborn it may also have mixed with sewage.
The classification decides the method. Clean water can sometimes be dried in place, but Category 3 water makes carpet, pad, insulation and drywall unsalvageable. Water also gets worse the longer it sits, so the classification can move upward while a basement waits. This is why wet-vacuuming a flooded basement with a household vacuum is a bad idea: it aerosolizes contaminated water and wrecks the vacuum.
What is the difference between flood damage and sewer backup for insurance?
Flood insurance covers surface water and overflowing waterways and is a separate policy that typically takes 30 days to take effect. Sewer and water backup is not automatically covered by a homeowners policy and is usually added by endorsement. Your insurer decides the claim, and the wording used to report the damage matters.
Michigan's Department of Insurance and Financial Services says water and sewer backup is not automatically covered under a homeowners or renters policy, and that federal flood insurance is a separate policy that typically takes 30 days to go into effect. Basement coverage under the National Flood Insurance Program is limited. Homes near some rivers may be required to carry flood insurance. The state regulator's consumer line is 877-999-6442, weekdays 8 to 5.
The state also advises against reporting a loss simply as a flood. Storm rainwater intrusion, a sewer backup or a failing sump pump may be covered under the policy, and each is a different cause. Nothing here promises a coverage decision; it is your insurer's call under your policy. What the crew can do is document the water line, the removed materials and the readings, and give you copies for the claim. Ask your agent whether your policy has a water-backup endorsement before the next storm.
What can be saved after a basement flood, and what has to go?
Concrete, block, poured walls and solid framing can usually be cleaned and dried, while carpet, pad, insulation, particleboard, paperboard and soaked drywall in Category 3 water are discarded. Contents depend on material: hard, nonporous items can be washed and disinfected, upholstered and cardboard items usually cannot.
A technician sorts the basement into what holds water and what does not. Poured concrete and block are hard and can be washed and disinfected. Dimensional lumber, such as joists and wall studs, can usually be cleaned and dried to the same readings as a dry area. Drywall, paneling, insulation and any engineered wood are absorbent and often fail in the first day or two, and once Category 3 water has soaked them they are removed.
Contents are the harder conversation. Washable plastic, glass and metal can be cleaned. Books, boxed papers, stuffed furniture and mattresses usually cannot be made safe. Photograph everything before it is moved, because you will want the list later. The same sorting logic applies to drying; see the structural drying page for what the readings need to show.
- Keep and clean: poured concrete, block, solid framing, metal, glass and hard plastic
- Usually discard: carpet and pad, insulation, particleboard, paperboard and soaked drywall
- Case by case: solid wood furniture, sealed items and documents, with a technician's advice
Which parts of the Dearborn area flood, and why?
East Dearborn sits lower than west Dearborn and was built before World War II, with sewers designed to the standards of that era. The city said its northeast and southeast ends took the worst damage in June 2021. Across Wayne County, low points along the Rouge and Ecorse Creek take water from upstream communities.
Dearborn's own flood information says later infill removed several surface streams that once led to the Rouge River, leaving fewer drainage options. The lower Rouge was straightened and a 4.2-mile section lined with concrete to move stormwater out quickly, which helps in a normal storm and gives little relief when the system is overwhelmed. Clay soil in the Ecorse watershed absorbs water poorly, so more of it runs off.
The pattern repeats across the region. Dearborn Heights is a low point in the Ecorse Creek and Rouge systems, and Hanover Street borders Ecorse Creek and is notorious for flooding. The Southfield Freeway at Outer Drive on the Dearborn border was closed for several days in early May 2019 and again in January 2020. In 2014 the August storm overwhelmed combined sewers across Wayne, Oakland and Macomb counties. A flood is a regional event, which is also why crews can be busy when it hits.
