Frequently asked questions about water quality | Brisbane City Council

Frequently asked questions about water quality

Below are frequently asked questions about water quality monitoring.

What is microbial contamination?

Microbial contamination refers to the presence of microbes such as viruses, bacteria and protozoa in the water.

How do you measure the microbial contamination of the waters?

The water is monitored for levels of bacteria known as enterococci. This is a widely used way to measure microbial contamination. Enterococci occur naturally in humans and animals and are generally contained in faeces. Enterococci are key indicators of other bacteria, viruses and protozoa that have the potential to cause disease in humans.

Where does microbial contamination come from?

Microbial contamination can come from stormwater runoff, faeces from domesticated and wild animals, leaking sewerage pipes, boating wastes, malfunctioning septic tanks, sewage treatment plant overflows and illegal sewer connections.

What causes high enterococci readings?

During and immediately after heavy rainfall, high enterococci readings and microbial contamination can occur through:

  • faeces from wild and domesticated animals washing from the catchment, through the stormwater pipe system and into our waterways
  • wastewater treatment plants and pumping stations operated by Queensland Urban Utilities in Brisbane. These are designed to overflow in certain situations to prevent raw sewage backing up into houses. Overflows can result in untreated sewage directly entering our waterways

During dry weather microbial contamination can still occur through:

  • electrical outages causing the wastewater treatment plants and pumping stations to temporarily stop working
  • broken sewer pipes, malfunctioning septic systems, illegal sewer connections or illegal dumping of sewage

When can I swim, boat and canoe in the water?

That depends on a number of factors. Check Council's water monitoring results for more information for your location and whether bacterial levels are high. If a warning sign is in place or results indicate high levels, or it is raining or has recently rained, avoid primary contact with the water.

What does primary contact mean?

Primary contact includes those activities where:

  • the whole body is immersed, or the face or other body parts are frequently immersed
  • the face is frequently wet from spray and it is likely that some water will be swallowed or inhaled 
  • water comes into contact with ears, nasal passages, or cuts in the skin

Typical primary contact activities include: 

  • swimming
  • diving
  • surfing
  • kite surfing
  • jet skiing
  • water skiing

What does secondary contact mean?

Secondary contact refers to activity in which only the limbs are regularly wet and greater contact including swallowing water or full immersion is unlikely.

Typical secondary contact activities include:

  • boating
  • fishing
  • wading
  • rowing

Can I eat fish caught in contaminated waters?

Yes, but Queensland Health recommends that all fish and seafood be properly cleaned and cooked before eating.

What type of diseases might I get if I undertake activities in water with microbial contamination?

There is an increased risk of infection if people who have a low immunity such as children, the sick and the elderly, come into direct contact with contaminated water. Symptoms may include diarrhoea, abdominal pain and cramps, fever and respiratory infections. Wound infections, dermatitis, conjunctivitis and ear, nose and throat infections may also occur.

If you experience these symptoms after having primary contact with contaminated waters, you are encouraged to:

How do I know if waterways are safe to enter?

It is not possible to know what the levels of contaminants are in a waterway at all times, and the results from the monitoring are only indicative of the levels of bacteria present at the time the sample was taken. These results can vary on a daily basis. If you use the waterway, you should always exercise caution, follow Queensland Health advice and read Council signs.

As a general rule do not enter waters during or up to three days after heavy rainfall. Always avoid swimming near stormwater pipe outlets.

What activities should I avoid if monitoring results show a high reading?

Typically, primary contact activities should be avoided, including swimming, diving, surfing, kite surfing, jet skiing and water skiing.

Under some circumstances when bacterial levels are extremely high, secondary contact activities should also be avoided, such as rowing, wading and fishing.

What is the best contact if I have questions about health issues due to waterway quality?

You can contact:

  • 13 HEALTH or 13 43 25 84
  • Queensland Health Public Health Unit, Brisbane northside on 07 3624 1111
  • Queensland Health Public Health Unit, Brisbane southside on 07 3000 9148

How can I access more information and updates?

Residents can contact Council on 07 3403 8888 or check the water quality monitoring results for regular updates.

12 October 2017