A man who had a "tsunami of sewage" pour into his swimming pool during the weekend's heavy rainfall says he is disgusted by the response from Sydney Water.
Sydney was battered by torrential rain which caused flash flooding and widespread power outages.
Castle Hill carpenter Steve Fender said stormwater mixed into a sewage line running around his backyard, which then overflowed his 50,000-litre pool on Sunday.
Sydney Water told the ABC this was not supposed to happen.
Mr Fender said the sewage also poured into his workshop, garage and the space under his house.
"I initially thought it was dirty water," he said.
"It wasn't until I looked over the fence that I could see it coming out of the sewer pipes.
"It was putrid, it smelt heavily of urine and the next day when it was almost 30 degrees [Celsius] you couldn't even go out there."
Despite raising concerns it was a serious health hazard, Mr Fender said Sydney Water only agreed on Thursday to come out to help with the clean-up and maintenance.
In the interim, Mr Fender drained and dumped about two buckets of chlorine into the pool which helped with the smell.
But a layer of contaminated water remains under his house and a repugnant odour has seeped through the floor and into his living room.
"There's about 18 houses worth of sewer in that one spot," he said.
Sydney Water apologised to Mr Fender and offered to assist him with costs associated with uninsured loss and clean-up for the pool and garden.
Mr Fender said he was still "absolutely disgusted" by the delayed response and questioned the viability of housing developments down the road.
A residential tower with up to 300 apartments has been proposed for the nearby metro station.
A Sydney Water spokesperson said it was "working as quickly as possible to respond" to the 6,750 requests for help it had received since the weekend.
It said crews investigated the overflow near Mr Fender's Castle Hill home and "found a choke caused by wet wipes had significantly contributed to the overflow experienced by these customers".
"In Sydney, the wastewater and stormwater systems are separate," a Sydney Water spokesperson said.
"However, when it rains, stormwater can enter the wastewater system."
The regulator said the systems could mix in several ways, including "illegal connections" or faults with wastewater pipes.
Sydney Water said it would roll out new "water and wastewater services to keep pace with rezoning of the land for new housing".ABC