Ms Malley said sewerage spread through the plane and passengers near the toilet were offered masks to deal with the stench.
She texted “Stuck in LA… 3 hours in to our flight they decide to turn around because the bathroom exploded and we were literally sitting in crap. 2 rows away and offered masks for the 3 hours back. YUCK!!”
Flight VA2 was heading to Sydney from Los Angeles via New Zealand early on Tuesday when the plumbing problems occurred.
Virgin Australia said the flight was forced back to Los Angeles due to leaking sinks, and denied that human waste reached the aisles.
“In accordance with standard operating procedures, the captain made the decision to return to port as a precautionary measure after two of the sinks on board were leaking,” the airline said in a statement.
“The onboard toilets operate on a completely separate drainage system,” the airline told The Sydney Morning Herald.
“As the issue was with the aircraft sink, and not the toilets, there was no incident of leaked human waste.”
Virgin said the long-haul flight was turned around for the comfort of passengers and the plane had since been cleared to return to service.
In a letter to affected passengers, Virgin Australia offered its “sincere apologies for the disruption you encountered”.
“Unfortunately the aircraft did need to return to Los Angeles due to an issue with plumbing in the fresh water overflow system on board and could not continue with the journey,” wrote ground operations manager Roger Lindeman.
“At no time was health or safety at risk to any persons on board the aircraft.”
The airline has also rescheduled the passenger’s flights, and offered a credit with the airline’s travel bank.