Category 3 means removal, not restoration
S500 defines Category 3 as grossly contaminated water that can carry pathogenic, toxigenic or other harmful agents. Sewage, toilet backflow from beyond the trap, ground surface water, and seawater all fall into it. The standard does not offer a dry-in-place option for porous materials in this category.
In practice that means carpet, pad, drywall below the line, insulation, and often the bottom plate. It means bagging in the room, not walking it through the house. It means negative air where the work area can be sealed.
Disinfection has a sequence
Remove the material, then clean the surfaces, then apply a disinfectant rated for the contamination, then verify. Applying a disinfectant over sewage-soaked drywall does nothing, because the contamination is inside the assembly.
Hard surfaces that stay, such as concrete, tile over slab, and metal framing, are washed and disinfected, then dried. We document what was removed, what was treated, and what readings closed the job.
Health and reoccupancy
Nobody should be in a sewage-affected basement without PPE, and that includes the homeowner who wants to help. If the loss is in a commercial kitchen or a building with a shared laundry, the building department and the health department may both have a say before reopening.
We will tell you when the space is safe to reoccupy based on the work completed and the readings, and we will put it in writing.
What happens to the material we remove
Removed material is bagged inside the work area and carried out through the shortest path to the exterior, not through the kitchen. Contaminated demolition debris is handled as contaminated waste, and the disposal record is part of the job file rather than something that disappears with the dumpster.
Framing and hard surfaces that stay are washed, then disinfected, then dried. We do not fog a basement and call it clean, and we do not apply a disinfectant to a material that is still saturated with sewage, because the contamination is inside the assembly and the surface treatment never reaches it.
Questions we get on this scope
Is a sewage backup an emergency?
Yes. Category 3 water gets worse with time and temperature. Every hour increases the contamination load and the amount of material that has to be removed.
Can you save my finished basement?
The finishes usually go. The structure usually stays after cleaning and disinfection. Framing that is pressure treated and can be washed may survive. Drywall, insulation, carpet and pad do not.
Do I need to leave the house?
If the affected area can be isolated and the HVAC does not distribute air through it, you can usually stay. If sewage reached a furnace, an air handler, or the only bathroom, you should not.
Does insurance cover sewage backup cleanup?
A sewer backup is usually excluded from a standard homeowner or commercial policy unless a backup endorsement was purchased. When it is covered, the endorsement typically carries its own limit. Read the endorsement limit before the work, not after.
How long does a sewage cleanup take?
A single basement room with concrete or tile surfaces usually clears in one to two days of work plus two to four days of drying. A finished basement with carpet, pad, drywall and insulation adds demolition and disposal time, and the dry can run five to seven days once the wet material is out.