Key takeaways
- ✓ Sewage is a biohazard — keep employees, customers and visitors away from the affected area and never handle the cleanup casually.
- ✓ Disconnect electrical appliances in the area, and turn off gas and power if the sewage has spread widely.
- ✓ Professional cleanup covers safe removal of water and contaminants, disposal of ruined items, disinfection of salvageable ones, and thorough drying.
- ✓ Common causes include clogs, grease build-up, tree roots in the sewer line, cracked pipes, poor joints and improper flushing habits.
- ✓ Untreated standing water leads to secondary water damage and mould, so speed matters twice over.
First, understand what you're dealing with
A backed-up drain in your business is stressful on its own. When actual sewage is involved, the situation changes character entirely: what seems like a simple plumbing issue quickly escalates into a hazardous one, and operations may need to stop until the premises are safe again. Sewage water is contaminated with bacteria, viruses and parasites that can cause illnesses such as gastroenteritis — which is why it should never be handled by just anybody.
Knowing what to do ahead of time is the best way to limit the damage. Here's the sequence.
Steps to take when a sewage backup occurs
- ✓ Restrict access. Keep employees, customers, clients and visitors well away from the affected area. Rope it off or lock it if you can.
- ✓ Disconnect electrical appliances in the area. If the sewage has spread widely, turn off gas and power to the affected part of the building.
- ✓ Stop adding water. Don't run taps, flush toilets or use appliances that drain into the blocked line.
- ✓ Call a professional cleaning company immediately. The sooner cleanup starts, the sooner your business reopens — and the less chance the backup leaves behind lingering odours and secondary damage.
You may have heard that non-porous surfaces can be treated with a household bleach solution — public health guidance suggests around one cup of bleach in 10 litres of water, left on the surface for about ten minutes. That's fine for a tiny, contained splash, but it is not a substitute for professional cleanup of a genuine backup. Sewage work needs protective equipment, controlled disposal and proper drying, and doing it yourself risks your health and everyone else's.
What the professionals will do
A trained sewage cleanup crew treats the job as decontamination, not cleaning. On a commercial callout they will:
- ✓ Safely remove all water and contaminants with extraction equipment.
- ✓ Remove items the backup has damaged.
- ✓ Dispose of anything that can't be salvaged — saturated porous materials generally can't be made safe.
- ✓ Disinfect the items that can be saved.
- ✓ Sanitise every affected surface, then dry and dehumidify the area so moisture doesn't linger in the structure.
What causes sewage backups in a business?
Part of preventing the next backup is knowing what triggers them. Keep an eye out for these, and deal with warning signs — slow drains, gurgling, recurring blockages — before they become an overflow:
- ✓ Clogs from improper flushing habits — wet wipes, paper towel and sanitary items are the usual offenders.
- ✓ Grease and fat build-up in the line.
- ✓ Tree roots that have infiltrated the sewer line.
- ✓ Cracked or deteriorated pipes.
- ✓ Improper joints and connections in the plumbing system.
- ✓ Irregular cleaning and poor maintenance.
How to prevent sewage backups
Nothing guarantees your business will never see a backup, but a few measures shift the odds strongly in your favour:
- ✓ Have your plumbing and sewer systems professionally inspected every year.
- ✓ Install a water pressure-reducing valve to lower the stress on the system.
- ✓ Have pop-up sewer release valves installed.
- ✓ Train staff on what can and can't go down the drains and toilets.
Don't forget the water damage
A sewage backup is also a water event. Standing water that isn't extracted and dried quickly soaks into flooring, walls and joinery, causing substantial damage to the property — and damp materials create the conditions for mould growth soon after. That's why proper cleanup always ends with drying and dehumidification, not just disinfection. If the backup has caused broader flooding, our water damage restoration and mould removal services pick up where the sewage cleanup ends.
Need a hand in Sydney or Regional NSW?
One Prime responds 24/7 across Greater Sydney & Regional NSW. We've handled the worst sewage situations commercial properties can produce, and our sewage clean-up team will remove the hazard, sanitise the site and dry it out properly so you can reopen with confidence. Call 1300 774 631 or contact us any time.
Frequently asked questions
What's the very first thing to do when sewage backs up in my business?
Keep everyone away from the affected area — employees, customers and visitors. Then disconnect electrical appliances in the space, turn off gas and power if the sewage has spread widely, stop using any drains on the affected line, and call a professional sewage cleanup company. Speed limits both the health risk and the property damage.
Can I just clean it up with bleach?
A bleach solution can disinfect a small splash on a hard, non-porous surface, but it can't make a real backup safe. Sewage soaks into porous materials, spreads contamination beyond what you can see, and leaves moisture behind that causes damage and mould. Professional cleanup involves extraction, controlled disposal, disinfection and drying — bleach alone does none of that.
Will a sewage backup cause mould?
It can. A backup is also a water event, and if standing water and soaked materials aren't extracted and dried quickly, the trapped moisture creates ideal conditions for mould growth. That's why proper sewage cleanup always includes drying and dehumidification, not just disinfection.
How do I stop sewage backups happening again?
Have your plumbing and sewer systems inspected annually and fix faults straight away, install a water pressure-reducing valve and pop-up sewer release valves, and train staff to keep grease, fats, wet wipes and other non-flushables out of the drains. No measure is a guarantee, but together they sharply reduce the risk.
Sources & further reading
This article is general information, not medical or legal advice. Last reviewed 28 February 2019 by the One Prime Solutions team.