The tertiary system is designed to reduce the risk of illness and death from water contamination by treating water in the same way as other household or industrial water systems.
However, as the tertial system was developed, it was also used to treat wastewater, which can contain chemicals and pathogens, and it is a potential source of water contamination.
The system also has the potential to cause harm to wildlife by altering the chemistry of water and releasing toxic chemicals into the environment.
The Australian Institute of Marine Science (AIMS) recommends that people use filtered water only when there is no other safe way to obtain water, and not to use tap water.
“The tertiary systems have the potential for serious harm to marine life,” said AIMS spokesperson Susan Withers.
“They can be harmful to fish and other animals.
They can also be harmful if they are released into streams and wetlands.”
AIMs says it has not yet come to a consensus on whether the tertials should be phased out.
In 2016, the Australian Government announced a $1.2 billion fund to replace and upgrade the system.
The new fund is expected to come into effect in 2019.
What is tertiary and how does it work?
There are two systems of tertiary treatments in use in Australia.
The first system uses a system of filters that separate water from wastewater and treat it for three months, followed by disinfection.
The second system uses chlorine and disinfection chemicals that kill bacteria.
When a system is operating at capacity, a second chlorine-based treatment system is activated and disinfected.
The tertials are designed to prevent water from entering groundwater, where microbes can grow and cause disease.
The AIM, a science organisation, is also urging water systems to use a chlorine-free system.
“These systems are not safe for human health and they are not appropriate for industrial or agricultural use,” said Ms Wither-Williams.
The NSW Environment Protection Authority says that tertiary wastewater treatment has been proven to be safe.
However it says it can’t provide a definitive answer on whether tertiary or filtered water should be used.
“We can’t really say how safe these systems are, because we don’t have a complete assessment of the evidence,” said Dr Helen Rutter.
“There’s also the risk that tertials may be used to remove chemicals from groundwater, which could have adverse health effects for animals.”
The AEMS says tertiary processes also release chemicals into streams, wetlands and waterways.
It also warns that untreated water can contain contaminants and pathogens.
“Wastewater treatment can contain bacteria, heavy metals, pesticides and pesticides that can cause respiratory problems for fish and mammals,” said Wither.
“It is not recommended for humans.”
The Environment Protection Agency says the water quality in NSW has improved in recent years.
“While we have seen significant improvement in our water quality, it is important to remember that water quality continues to be an important issue and water treatment and remediation work is continuing,” a spokesperson said.