What is sewage?
Sewage is faecal matter (poo or sometimes known as nightsoil) or urine (wee).
According to the Health Act 1911 (external link), it can also be any waste composed wholly or partly of liquid.
What is a sewage spill?
A sewage spill is the overflow, leaking or spillage of sewage from a sewer line or wastewater treatment plant, or a wastewater receptacle (container).
Sewage spills can be into/onto a:
- water body
- recreational waterway
- land area
What causes sewage spills to occur into recreational waterways and what is their affect?
A sewage spill can be caused when wastewater treatment plants or pump-stations experience a mechanical fault such as loss of electrical power.
Broken or blocked sewer mains can also cause sewage spills.
Sewage may enter the waterway directly from the point of rupture or overflow, or through stormwater drains.
This can make the water unsafe for swimming and other forms of recreation such as water-skiing, jet-skiing and diving. Secondary contact activities such as boating, fishing and wading may also be affected.
Will I get sick if I swim in water contaminated with sewage?
Yes. If you have contact with or swallow water that is polluted with sewage it can make you very sick. Some illnesses may include:
- gastroenteritis (diarrhoea, vomiting)
- viral infections such as hepatitis
- infections of the skin or eyes.
What happens when a sewage spill occurs?
There are many different organisations involved when a sewage spill occurs.
The roles and responsibilities of various government agencies is outlined in the Wastewater Overflow Response Procedures V2.2 March 2013 (PDF 911KB).
One of the primary responsibilities is making sure the public is aware when a sewage spill occurs.
How will I know if there has been a sewage spill?
When a sewage spill occurs the community will be informed as a top priority.
Warning signs and media releases will be issued to let you know the spill has happened.
If you ever see a health warning sign along the river or beach make sure you follow the advice and do not go swimming.
When will the water be safe to swim in?
After a sewage spill, it usually takes from 48 to 72 hours for a water body to return to a safe condition. Sometimes it can take a week or more.
A number of factors will determine when a contaminated water body will return back to a safe condition. These include:
- salinity (the more salt the better)
- sunlight (the more sun the better)
- tidal movement
- weather conditions
- the volume of the spill.
The Department of Health will not give the water body the all clear until it has been determined to be safe for recreational purposes.
Can I eat fish or shellfish collected from water contaminated with sewage?
Evidence suggests that eating fish or crabs taken from water contaminated with sewage will not result in any known health effects as long as standard hygiene measures are followed.
- washing your hands with warm water and soap after handling fish or crabs
- thoroughly washing fish with clean water before cooking
- cooking using correct times and temperatures.
You should not eat any filter feeding shellfish such as oysters or mussels taken from water contaminated by sewage because:
- They feed by drawing water through a membrane and trapping food for digestion. Therefore, they draw contaminated water through the flesh that you'll end up eating – this is particularly dangerous if consumed raw because of the disease causing bacteria associated with sewage.
- Organisms like viruses (especially Hepatitis A and Norovirus) are trapped in the flesh of the shellfish and are not killed by the normal cooking process of shellfish.
The Department of Health does not support the collection of wild shellfish from recreational waters surrounded by urban, industrial and commercial areas because the safety of eating wild shellfish cannot be guaranteed.
Further health information about the collection of shellfish from the wild can be found in the Wild shellfish collection (PDF 68KB) pamphlet.
What should I do if I see a sewage spill?
If you notice sewage draining into a natural water body, you should immediately contact:
- Water Corporation
- (Faults, emergencies and security)
- T: 13 13 75 (24 hours)
- Department of Environment Regulation
- (Emergency Pollution Response)
- T: 1300 784 782 (24 hours)
You may also advise:
- Department of Health
- Environmental Health Directorate
- (Monday to Friday, 8.30am-5pm)
- T: 9388 4999
- Health Duty Officer
- T: 9328 0553 (24 hours)
- Swan River Trust 9278 0900 (If sewage spill is in the Swan or Canning Rivers)
- Your local council
Where to get help
If you have been swimming in water that is known to be contaminated with sewage and you are experiencing symptoms of an upset stomach and diarrhoea, you are advised to:
- See your doctor.
- Visit a GP after hours.
- Ring healthdirect Australia on 1800 022 222.
- Do not swim in water that has been contaminated by a sewage spill.
- After a sewage spill, it usually takes from 48 to 72 hours for a water body to return to a safe condition.
- Do not eat any filter feeding shellfish such as oysters or mussels taken from water contaminated by sewage.
Environmental Health Water Unit
This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.