What has to be thrown away after a sewage backup.

The rule is porosity, not appearance. Anything absorbent that took contaminated water comes out: carpet and its pad, drywall from the water line upward, insulation, particleboard, mattresses, upholstered furniture. Anything hard and non-porous can be cleaned and disinfected: concrete, tile, sealed metal, glass, solid plastic, finished hardwood in some cases.

Something looking clean is not the test. It cannot be scrubbed if the water went into it rather than onto it.

Why the rule is removal rather than drying

With clean water the goal is to dry material fast enough to keep it. With category three water there is nothing to dry toward, because the problem is not moisture. It is what came in with the moisture and is now inside a material you cannot reach.

This is the single biggest difference between a sewage job and an ordinary water damage job, and it is why a sewage estimate is mostly demolition where a water estimate is mostly equipment.

Goes, in almost every case

• Carpet and carpet pad. The pad is a sponge and cannot be cleaned in place. Carpet that was glued down goes with it.
• Drywall, cut out to a line well above where the water reached, usually a foot or two, because the paper facing wicks upward and the cavity behind is wet higher than the surface shows.
• Insulation in any wet wall cavity, all of it in that bay, not the stained part.
• Particleboard and chipboard, including cabinet bases, kickboards, and most flat pack furniture. It swells and does not recover.
• Mattresses and box springs.
• Upholstered furniture that absorbed it. A sofa with wet legs is a different question from a sofa that sat in it.
• Laminate and engineered flooring, and the underlay beneath it, because the water spreads sideways under it with no way out.
• Food, including anything in a sealed package that was submerged, and anything in a cardboard box.
• Cosmetics, medicines, and baby items that were touched.
• Toys that are soft or that hold water inside.
• Paper, books, and cardboard.

Can usually be cleaned and kept

• Concrete and unsealed masonry, cleaned and disinfected, though it needs proper drying afterwards.
• Ceramic and porcelain tile on a hard substrate, with the grout cleaned. Tile over a wooden subfloor is a judgment call, because what is under it matters more than the tile.
• Sealed metal, glass, hard plastics.
• Solid wood furniture, if the finish is intact and it was not submerged for long.
• Clothing and linens, washed hot and separately, if they are launderable. Anything dry clean only that was soaked is usually not worth the cost.
• Dishes and cutlery, washed and sanitized. Discard anything wooden, and anything plastic that is scratched.

The judgment calls

Hardwood floors. Sometimes salvageable if the water was on them briefly and the finish is sound, often not if it went between the boards or reached the subfloor. This is a genuine assessment rather than a rule, and it is worth getting a second opinion, because floors are expensive and the industry default is removal.

Solid wood furniture with fabric. The wood can be cleaned. The fabric part is the same call as any upholstery.

Things with sentimental value. There are specialist restoration services for documents, photographs, and textiles, including freeze drying. It costs more than the item is worth in every case except the ones where it does not. Ask before anything goes in a dumpster.

Appliances. Anything with a motor or a control board that was submerged is usually finished, and even where it runs, the risk sits in the parts you cannot disinfect. A dishwasher or a washing machine that took contaminated water inside the drum is a replacement.

Photograph it before it goes

Every item, before it leaves the house. Wide shots of the room, then the pile, then individual shots of anything worth more than a token amount.

This is the evidence, and unlike a burst pipe there is no way to reconstruct it later, because the entire point of the exercise is that the evidence goes to the curb.

Write a list as you go: item, rough age, rough replacement cost. Doing it at the time takes an hour. Doing it from memory in three weeks costs you money, and incomplete documentation is one of the four common reasons these claims fail.

Whether any of it is paid for turns on one thing: most policies exclude backup unless the endorsement was bought.

Disposal

Ask the contractor or the local authority where contaminated material goes. Some municipalities require it bagged, some want it separated from ordinary bulk waste, and a few will collect it after a declared event. Do not leave soaked material sitting in the yard, because it stays wet and it attracts animals.

The short version

Porous absorbed it and goes. Hard non-porous can be cleaned and stays. Cut drywall well above the line, take all the insulation in that bay, and treat particleboard as lost. Photograph and list everything before it leaves, because after that there is nothing to show anyone.