Polybutylene pipe leaks causing major damage in Darwin homes
On a sticky afternoon during northern Australia's 2021 build-up season, Edith Heiberg returned home to find her ceiling weeping with water.
"It was raining inside," she said.
The monsoon season had arrived early, inside Ms Heiberg's home.
"It was a downpour," she said.
"You could hear the sound of it hitting the tiles.
"The water was cascading out the bedroom door, down the step into the lounge room."
Ms Heiberg and her family had recently moved to Darwin's satellite city, Palmerston, and were new to the tropical climate.
A warning sign, initially thought to be seasonal mould, ended up being a leaking polybutylene pipe.
Mick Summerton runs his plumbing business in the Top End, and has been in the industry for 11 years.
For most of that time, he has attended homes with the same emergency.
"You wouldn't go through most weeks without going to at least one job … where they've got a leak, or the ceiling's collapsed through the lounge room," he said.
"It's letting go all over the place."
Chief executive of Master Plumbers South Australia and the Northern Territory, Andrew Clarke, said the leaks prevalent in the Top End "were not occurring in the joints, which is a traditional place where a leak would occur".
"It is actually happening along the pipe, with no particular consistent location along that pipeline," he said.
"If it was a joint, you could possibly question whether it was a plumber's installation process, but in this particular case, it's quite evident that it's the product that's failing, not the plumbers."
Polybutylene pipes aren't the only type of piping that has "issues", according to James Gong, a senior lecturer in water engineering at Deakin University.
"For plastic pipes, the degradation process is mainly due to oxidation," he said.
Dr Gong said the oxidation could be caused by many factors.
"The chlorine inside the water can actually accelerate the oxidation process, the UV in light can accelerate the oxidation, high temperatures can accelerate it."
He said more research was needed in Australia into plumbing systems.
"Plumbing systems and … technologies have evolved significantly in the past three decades, but our plumbing codes and standards haven't really changed much since the 1970s," he said.
"In Australia, if you're looking into the history of plumbing standards and codes, most of the research was done in the US, back in the 1940s."
Polybutylene pipes ceased being sold in the US after a 1995 class action against a manufacturer settled for $1.3 billion.
The same pipes were removed from Canada's standard plumbing code in 2005.
Western Australia's building regulator is currently investigating the cause of polybutylene pipe leaks, in houses predominantly built in 2019 and 2020.
Construction experts warn leaky buildings that have been constructed with improper waterproofing are reaching "pandemic proportions" in what some fear could take a catastrophic building collapse before the government improves building practices. 
It has so far found the leaks were "principally from Pro-fit pipes manufactured by Iplex Australia between mid-2017 to mid-2022".
Iplex Australia stopped selling the product in May 2022 and its parent company, Fletcher Building, has proposed interim arrangements with two large WA builders to help them respond and assist impacted homeowners.
The ABC is not suggesting Pro-fit pipes have failed in Darwin.
The body which represents polybutylene manufacturers, the Plastics Industry Pipe Association of Australia, did not respond to requests for comment.
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