Yes, but the blockage itself does not usually cause illness. The risk arises when it exposes you to sewage, contaminated wastewater, persistent dampness or irritating sewer gases. A slow drain is generally less concerning than an overflow, leak, strong sewage odour or wastewater entering the home.
How can exposure affect your health?
Contact with sewage-contaminated water or surfaces may cause gastrointestinal illness, skin irritation or infection, particularly after splashes or hand-to-mouth contact. Persistent dampness and mould can aggravate asthma, allergies and other respiratory symptoms.
Sewer odours may cause nausea, headache or irritation, but smell alone cannot identify a gas or establish whether its concentration is dangerous.
Treat a blocked drain as a potential health hazard if there is:
- sewage or wastewater on indoor surfaces
- contamination near food, medicines or children’s belongings
- a recurring overflow or leak
- persistent dampness or visible mould
- a strong sewage odour in occupied rooms.
Children, older people, pregnant people and anyone with a weakened immune system or respiratory condition should avoid the affected area.
What should you do after a backup?
Keep people and pets away, limit further wastewater flow and arrange professional assessment.
- Stop using affected fixtures: Do not flush toilets or use connected sinks, showers, washing machines or dishwashers.
- Avoid contact: Do not walk through or handle sewage. After incidental skin contact, wash thoroughly with soap and clean water.
- Protect food and personal items: Keep wastewater away from food, utensils, medicines and children’s belongings. Seek appropriate cleaning or disposal advice for contaminated items.
- Do not use drain chemicals: Mixing products or adding them to standing wastewater can create hazardous fumes or splashes.
- Avoid electrical hazards: If water is near power points, wiring or appliances, do not enter the area or touch electrical equipment. Call Triple Zero (000) if there is immediate danger; otherwise seek advice from a licensed electrician.
- Ventilate only if safe: Open an accessible door or window without entering the contaminated area.
Do not attempt to diagnose or repair a sewage backup yourself. Sanitary plumbing and drainage work requires appropriately licensed help, while widespread indoor contamination may need specialist cleaning.
When should you get help?
Seek medical advice after swallowing contaminated water, significant sewage exposure, or a splash to the eyes or mouth. Also seek advice if vomiting, diarrhoea, skin irritation, breathing symptoms, headache or nausea develops. Call Healthdirect on 1800 022 222, particularly if the person is vulnerable or symptoms persist.
Call 000 for severe breathing difficulty, collapse or another medical emergency.
Arrange urgent plumbing help for an active sewage backup, repeated overflow, wastewater entering the building or several fixtures backing up together. Stop using the fixtures and contact our licensed Sydney plumbing team for assessment.