How 376 old, leaking septic tanks in Manningham are contaminating Melbourne waterways

CORRECTION: A previous version of this story incorrectly claimed Yarra Valley Water carried out inspections of septic tanks in Manningham, rather than Manningham Council as the responsible authority. Council has not issued an ultimatum to impacted properties and, while these old tanks are being gradually replaced, it is not illegal to own or operate one. We regret these errors.

Septic tanks being discharged into stormwater drains have helped push the risk to human health from water channels like Mullum Mullum Creek to high, with 376 Manningham properties deemed to be non-compliant.

💩 What is a septic tank? A septic tank is an onsite wastewater management system which treats or otherwise houses wastewater from a property, including water and human waste from showers, toilets and sinks.

• Pumping out a septic tank generally costs between $300 and $800 per service – or about $320 if serviced every three years and calculated as an annual cost.

🚽 Forcing safer flushes: On November 25, Manningham Council voted to approve an updated Onsite Wastewater Management Plan, detailing actions to take until 2030.

• The council will also continue to advocate for Yarra Valley Water to carry out the connection themselves if the owner has failed to comply.

✉️ Naughty neighbours: In areas which recently received new sewerage systems, homeowners have decided to keep using 577 old septic tank systems instead of making the change to the new pipes.

• Between 1970 and 1998, homes without access to Melbourne’s main sewerage network were legally allowed to install systems that discharge untreated greywater from sources like showers or sinks and/or treated toilet waste into stormwater drains.

• However, Manningham Council has identified 376 systems are non-compliant with current standards.

🤢 What’s the harm? Council’s plan outlined the risk to human health from waterways near these property owners was currently at a high level.

• Older or poorly installed septic tanks can be a risk to human health and the environment, with potential impacts including exposure to dangerous microorganisms that can cause a range of illnesses or viral infections.

• “It’s not a happy environment for the little fish or for anyone going down to the Mullum Mullum Creek or the Yarra,” said Manningham councillor Andrew Conlon.

Everyone’s responsibility: Manningham Council deputy mayor Deirdre Diamante said she was “cross” that so many property owners decided to retain non-compliant septic tanks rather than switch to the safer option, calling on the community to take better care of the local environment.

• 🗣️“It’s an environment we need to have for our children and grandchildren and great-grandchildren,” said Diamante.

💰 Switch vs stay? Many homeowners retain their septic tank instead of switching over to sewerage as water bills increase, while costs to remove their existing septic tank and connect to the main sewerage can range from $3,000 to $15,000.

⏭️ What’s next? Yarra Valley Water (YVW) is currently working on designs for a new sewerage system for Park Orchards and parts of Ringwood North, with construction expected to commence in late 2027.

• Manningham Council director of city planning and liveability Andrew McMaster said the council “remains committed to encouraging property owners to connect to the main sewerage network if they have the option”.

• “We will continue to support Yarra Valley Water in their efforts to increase connection rates across Manningham,” McMaster told the Eastern Melburnian.