An inspection chamber rim shows how determined tree and grassroots drawn to moisture can find their way into tiny cracks in our sewer network and keep growing. Picture: SA Water.
Tree roots are largely to blame for a huge jump in sewer blockages across SA over the past year, with more resources being invested into maintaining hotspot areas in response to the spike.
SA Water data reveals sewer main blockages related to tree roots have increased by around 40 per cent.
It comes after the government department took to social media to urge SA residents to carefully consider the trees and shrubs they plant on the properties.
Posted with photos of grassroots in an inspection chamber and a pipe, it said choosing carefully would ensure plants don’t invade and destroy the state’s sewerage network.
An SA Water spokesperson said tree root intrusion was the leading cause of blockages in the statewide sewerage network, accounting for around 65 per cent of incidents each year.
“During the past 12 months, we’ve seen a significant increase in blockages across the state, largely driven by prolonged dry conditions,” the spokesperson said.
Grassroots in the sewer network. Picture: SA Water.
“Compared to the previous financial year, sewer main blockages have risen by almost 20 per cent, with tree root-related blockages alone increasing by around 40 per cent.
“In very dry conditions, tree roots naturally seek out moisture and can enter sewer pipes through small joints, particularly in older infrastructure.
“Once inside, they can grow quickly and restrict the flow of wastewater, potentially leading to blockages and overflows.
“From January 1 to December 10, 2025, we recorded 5167 sewer main blockages across South Australia, with 3342 – or around 65 per cent – directly caused by tree roots.”
The spokesperson said a specialised crew and equipment were deployed when blockages occurred to clear roots and assess pipe condition.
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They have increased resourcing in response to the recent spike in incidents and continue to invest in preventative cleaning in known hotspots, they said.
“During 2024-25, the total cost incurred by SA Water for sewer network incidents caused by tree roots was more than $11.3 million,” the spokesperson said.
While there was no list of trees that are universally suitable across metropolitan Adelaide, the spokesperson said residents could carefully select species for their area to significantly reduce the risk of future issues.
“We offer a dedicated tree planting guide, which recommends a wide range of suitable trees and shrubs and outlines safe planting distances from sewer pipes,” they said.
“The guide includes more than 200 species that can generally be planted without approval when appropriate clearances are maintained.
An inspection chamber rim covered in roots. Picture: SA Water.
“Customers can also use our online Healthy Pipes tool to identify where sewer pipes are located on or near their property, helping them make more informed planting decisions.”
According to water industry regulations, trees and shrubs must not be planted closer than 1m to any water main or customer connection without written approval.
“In addition, we are trialling new approaches such as installing root barriers, designed to prevent tree roots from reaching nearby sewer infrastructure while maintaining the health of the tree,” the spokesperson said.
Last year, experts urged Australian homeowners to check their backyards after shocking footage of a 5.5m root system was extracted from a water tank.
Elliot Aisthorpe of Big Country Earthworks shared jaw-dropping footage, warning it could happen to anyone who planted trees with invasive roots near their property.
“This is a great example why you should never plant trees with invasive roots near your home. You can just see what sort of damage they’re going to cause,” he warned.
Elliot Aisthorpe of Big Country Earthworks shared jaw-dropping footage of the two-storey high monster root system pulled out of a backyard water tank. Source: BigCountryEarthworks/TikTok
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