Written by Katie Welch, Senior Biohazard Cleaning Technician · 8+ years in the industry
No. Carpet and underlay that has been in contact with sewage can’t be made safe and must be thrown away. Sewage is “Category 3” water, which means it carries bacteria and viruses that soak deep into the fibres and backing, where cleaning can’t reach. Hard surfaces such as tiles, vinyl and sealed concrete can usually be cleaned and disinfected. Laminate, chipboard and soaked plaster usually need replacing.
If a sewage leak has affected your home, it’s common to wonder “can I keep the carpet?” It may look as if it could be cleaned, but the problem is the parts you can’t see. This guide goes through each type of floor and wall, and what can and can’t be saved.
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Why sewage-soaked carpet can’t be cleaned
The water restoration industry sorts water damage into three categories:
- Category 1: clean water, such as a burst supply pipe.
- Category 2: grey water, such as a washing machine leak.
- Category 3: black water. This includes sewage, toilet overflows with waste, and flood water from outside.
Category 3 water carries E. coli, norovirus, hepatitis A and other germs. Carpet soaks up sewage like a sponge. It goes through the pile, into the backing, then the underlay, until it reaches the floor beneath. That’s why even a professional carpet cleaning machine can’t reach all of it.
Industry standards advise that all carpet and underlay affected by Category 3 water should be safely removed and disposed of.
There’s also the smell. Sewage in carpet backing keeps smelling for weeks, especially once the heating is on.
What can be saved, and what has to go
| Material | Can it be saved? |
|---|---|
| Carpet | NoFibres and backing hold sewage that can’t be removed. |
| Underlay | NoFoam and felt soak the sewage up completely. |
| Rugs | Usually noOnly a small, washable rug might be saved; most can’t. |
| Laminate | Usually noWater gets into the joints and swells the board core. |
| Engineered wood | SometimesDepends how long it was wet and how far it soaked in. |
| Solid floorboards | OftenCan be cleaned, disinfected and dried if not rotten. |
| Chipboard floor panels | Usually noThey swell and break down when wet. |
| Ceramic tiles | YesClean, disinfect and check the grout. |
| Vinyl or lino | OftenYes if sealed; no if sewage got underneath. |
| Sealed concrete | YesClean, disinfect and dry. |
| Plaster and plasterboard | It dependsSoaked plasterboard is cut out; solid plaster may dry out. |
What about sewage under floorboards?
This is the most common hidden problem after a sewage leak. Sewage runs through the gaps between floorboards straight into the void underneath. If it isn’t cleaned out at the source, it sits there and smells. It can also lead to damp and rot.
At the start of a sewage job, we always lift the boards first to check the void. We then remove contaminated material and clean and disinfect the subfloor. We use Virosol first to break down the dried waste, followed by Byotrol to disinfect. The space then has to dry out fully before the floor goes back down.
We lift the boards and clean the void
Contaminated material removed, the subfloor cleaned, disinfected and dried before anything goes back down.
Has sewage soaked into the walls?
If sewage touched the walls, look for a tide mark. Plasterboard soaks water up like a wick, often well above the visible line.
- Plasterboard: wet sections are cut out and replaced, usually measured with a margin above the water line.
- Solid plaster on brick: can sometimes be cleaned, disinfected and dried out. It may need re-plastering if it stays damp or stained.
- Skirting boards: MDF skirting usually swells and needs replacing. Solid wood can often be cleaned.
Walls must be fully dry before redecorating. Painting over damp plaster traps the smell and the moisture, making them harder to remove.
Why you shouldn’t try to save it yourself
- Household carpet cleaners and steam cleaners spread contamination rather than remove it.
- Bleach doesn’t reach into underlay or the subfloor.
- Lifting sewage-soaked carpet releases contaminated water and particles.
- Contaminated waste has to be disposed of legally, as it’s classed as a biohazard.
If you need to deal with a small leak before help arrives, read how to clean a sewage leak safely.
Will insurance pay to replace the carpet?
Most buildings insurance policies cover sewage damage, including replacing flooring. In a rented home, carpets the landlord supplied are usually covered by the landlord’s insurance. Not sure who’s responsible? Read who is responsible for a sewage leak. Before anything is thrown away:
- Take photos and videos of all the affected areas.
- Keep a small cut sample of the carpet in case your insurer asks for one.
- Get an itemised quote for the clean-up.
We provide photo reports and waste transfer notes that insurers and loss adjusters accept. Find out more about our sewage clean-up service.
Frequently asked questions
Do I need to replace carpet after a sewage leak?
Yes. Carpet and underlay touched by sewage can't be made safe by cleaning, because bacteria soak into the backing and underlay. They should be safely removed and disposed of.
Can you clean carpet after sewage?
Not safely. A deep clean may make it look better, but bacteria and viruses stay in the backing and underlay, and the smell will return.
What is Category 3 water damage?
Water that's grossly contaminated, such as sewage, toilet overflows containing waste, or flood water from outside. Porous materials it touches, like carpet and underlay, need to be disposed of.
What happens if sewage gets under the floorboards?
It collects in the void below and keeps smelling. The boards need lifting so the void can be cleaned, disinfected and dried.
Can sewage soak into plaster?
Yes. Plasterboard wicks water up above the visible line and usually needs cutting out. Solid plaster can sometimes be cleaned and dried out.
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