Sewage Backup in Your Home: What to Do (and What NOT to Do)

You’ve just walked into your kitchen and there’s brown water bubbling up from the drain. The smell hits you before you even see it. Your first instinct is to grab a mop.

Don’t.

That single decision could put you in hospital. Sewage isn’t dirty water. It’s a biological hazard containing bacteria, viruses, and parasites that can cause serious illness within hours of contact. What you do in the first 30 minutes matters more than anything that happens afterwards.

We’ve attended over 400 sewage incidents across Bristol in the last 25 years. Here’s exactly what to do, what to avoid, and when to call for help.

Immediate safety: protect yourself first

Before you do anything else, get everyone out of the affected area. Not just out of the room. Out of the ground floor if the backup is significant.

Don’t touch the water. Sewage contains Category 3 contaminants. That’s the worst classification. Even a small splash on your skin can introduce E.coli, Salmonella, or worse into your system. Children, elderly family members, and anyone with a weakened immune system are at particular risk.

Turn off the electricity. If the water level is anywhere near plug sockets, light switches, or appliances, kill the power at the consumer unit. If your consumer unit is in the affected area and you can’t reach it safely, call your electricity supplier’s emergency line. Do not wade through sewage-contaminated water to reach it.

Keep children and pets well away. This isn’t something kids should be near. Close doors, put up barriers, whatever it takes. A toddler who puts contaminated hands in their mouth could end up in A&E.

Open windows if safe to do so. Sewage produces hydrogen sulphide and methane gases. In enclosed spaces, these can cause headaches, nausea, and in extreme cases, loss of consciousness. Get air moving through the property.

Don’t eat or drink anything that’s been in the affected area. If flood water has reached your kitchen cupboards, bin the food. All of it. Sealed tins might be fine after disinfection, but anything in cardboard, paper, or plastic bags goes straight in the bin.

What NOT to do: the mistakes that make things worse

Every week we arrive at a sewage job where someone’s already made it ten times harder to fix. Here are the most common mistakes.

Don’t mop it up. A mop pushes contaminated water into flooring, grout, and skirting boards. You’re spreading the contamination, not removing it. You’re also exposing yourself to pathogens through splashing. That mop then becomes biohazardous waste itself.

Don’t pour bleach into the water. Bleach doesn’t neutralise sewage. It reacts with ammonia in the waste to produce chloramine gas, which is toxic. We’ve attended a job near Gloucester Road where a homeowner used three bottles of bleach and gave herself chemical burns to her airways. Don’t do it.

Don’t flush toilets or run taps. If your drains are backed up, adding more water makes everything worse. The blockage isn’t going to clear itself with more pressure. You’ll just increase the flood level.

Don’t use your household vacuum. Your Henry hoover isn’t designed for contaminated water. You’ll destroy the machine and create an aerosol of sewage particles that spreads throughout the house. Honestly, we’ve seen people do this more times than you’d believe.

Don’t rip up carpet or flooring yourself. Disturbing contaminated materials without proper PPE releases bacteria into the air. The underlay beneath carpet acts like a sponge for sewage and pulling it up sends a cloud of contamination airborne.

Don’t use fans to dry the area. Same problem. Fans spread contaminated air particles through the property. You might dry the visible water, but you’ve just pushed the contamination into every room.

Don’t wait and hope it dries out. Sewage contamination doesn’t go away when the water evaporates. The bacteria, viruses, and chemical residue remain in every surface the water touched. And within 24 to 48 hours, secondary mould growth starts. If you’re dealing with mould after flooding, we’ve written about sewage contamination health risks that explains why this combination is so dangerous.

First steps you CAN take safely

You’re not completely helpless. There are things you can do while waiting for professional help.

Wear rubber boots and heavy-duty rubber gloves. Not washing-up gloves. Proper ones that go past your wrists. If you have safety goggles, wear those too. Waterproof clothing if possible.

Document everything. Take photos and video of the flooding from every angle before anything gets moved or cleaned. Photograph water levels, where the water entered, damage to belongings, and the source if visible. This is critical for insurance claims and for establishing whether your water company is responsible.

Note the time and date it started. Write down when you first noticed the backup, how quickly it rose, and any events that might have caused it. Heavy rain? Neighbour having building work done? This information matters later.

Move undamaged valuables to higher ground. If you can safely reach items that haven’t been touched by the water, move them upstairs or onto tables. Don’t wade through the water to rescue things. Nothing you own is worth a serious infection.

Call your insurance company. Ring them as soon as possible. Most policies have specific time limits for reporting water damage. Take the reference number and keep records of every conversation.

Call a specialist sewage cleanup company. Not a general cleaner. Not a plumber. A company with biohazard training, proper PPE, and specialist extraction equipment. We operate an emergency line at 0808 303 7072 for exactly these situations, available round the clock.

The professional cleanup process

Here’s what happens when a proper sewage flood cleaning team arrives. This is what you’re paying for, and why it matters.

Assessment and containment. We assess the extent of contamination, identify the source, and isolate the affected area. Containment barriers stop the contamination spreading to clean parts of the property during cleanup.

Water extraction. Industrial wet vacuums and submersible pumps remove the standing water. These are specialist machines rated for biohazardous liquids, not the kind you hire from the tool shop.

Removal of contaminated materials. Anything porous that’s been in contact with sewage usually needs removing. Carpet, underlay, plasterboard below the water line, insulation, chipboard flooring. We remove it, bag it as hazardous waste, and dispose of it through licensed facilities.

Deep cleaning and biocidal treatment. Every surface gets cleaned with professional-grade biocidal agents. Not household disinfectant. Hospital-grade antimicrobial solutions that kill the specific pathogens found in sewage. Walls, floors, joists, concrete, pipework, everything the water contacted.

Structural drying. Industrial dehumidifiers and air movers bring moisture levels in walls, floors, and structural timbers back to acceptable levels. This takes days, not hours. We monitor with moisture meters until readings are where they need to be.

Air scrubbing. HEPA filtration units run throughout the process, capturing airborne particles down to 0.3 microns. This deals with the microscopic contamination you can’t see or smell.

Clearance testing and certification. Once complete, we test surfaces and air quality to confirm contamination levels are safe. You get a written report confirming the property is fit for occupation. Your insurer will want this.

The whole process typically takes between 2 and 5 days for an average domestic property. Severe cases take longer.

Health risks: what sewage actually does to you

This isn’t scare tactics. This is what we’ve seen happen to people who tried to clean up sewage themselves or ignored the problem.

E.coli. Causes severe gastroenteritis. Certain strains can lead to kidney failure, particularly in children. Present in virtually all sewage.

Salmonella. Vomiting, diarrhoea, fever. Can be serious in young children and elderly people. Infection through skin contact with contaminated water, not just ingestion.

Norovirus. Incredibly infectious. A tiny amount of contaminated material can infect an entire household. Survives on surfaces for days.

Hepatitis A. Attacks the liver. Symptoms can take 2 to 7 weeks to appear, meaning you might not connect your illness to the sewage exposure. Spread through contact with contaminated water.

Leptospirosis. Carried in rat urine, which is present in sewage systems. Enters through cuts, scratches, or mucous membranes. Can cause organ failure in severe cases. About 50 people a year are hospitalised with this in the UK.

Parasites. Cryptosporidium and Giardia are common in sewage. Both cause prolonged gastrointestinal illness. Cryptosporidium is resistant to chlorine, which is another reason bleach doesn’t work.

Beyond the biological hazards, sewage contains industrial chemicals, pharmaceutical residues, and heavy metals. Long-term exposure to contaminated environments has been linked to respiratory problems and skin conditions.

For a detailed breakdown of these risks and why specialist treatment is non-negotiable, read our full guide on sewage contamination health risks.

When to call for help

Call immediately. That’s the honest answer.

If you’ve got sewage backing up into your home, this isn’t a wait-and-see situation. Every hour that contaminated water sits in your property, it’s soaking deeper into materials, bacteria are multiplying, and the final cleanup cost is climbing.

Bristol Cleaning Heroes are sewage flood cleaning specialists with £2M insurance cover and 25 years’ experience dealing with exactly this. Call us on 07985 505061 or our emergency line on 0808 303 7072. We’ll talk you through immediate safety steps on the phone and get a team to you as fast as possible.

Your health comes first. Your property comes second. Everything else can wait.