Significant spike in sewer blockages amid prolonged dry

SA Water is urging South Australians to be vigilant with what goes down their plumbing after recording a significant spike in sewer main blockages over the past 11 months – driven by increased tree root intrusion from dry conditions.

In 2024-25, there were 5,132 sewer main blockages reported across the state, up from 4,383 compared to the previous financial year.

The most common cause remains tree roots, responsible for nearly two-thirds (3,275) of all sewer blockages recorded in 2024-25 – a notable increase from 2,352 the year prior.

SA Water’s Senior Manager of Infrastructure, Planning and Strategy Dr Daniel Hoefel said the dry weather has played a significant role in the increase.

“Recent sustained dry conditions have prompted trees to seek moisture from within our sewer network, pushing roots into pipes and causing blockages and in some case, sewage overflows,” Daniel said.

“This trend is especially visible in suburbs such as Morphett Vale, Flagstaff Hill, Happy Valley, Athelstone and Rostrevor – the worst affected areas for tree root intrusion.

“We encourage our customers to use our online tree planting guide when planting new trees and shrubs on their properties, to ensure selected species that can minimise tree root intrusion on their private pipework or our sewer network.”

Non-flushable items like wet wipes, sanitary pads and tampons also continue to be a concern for SA Water’s sewer crews, with 564 pipe blockages caused by these materials, also in the past 12 months.

Suburbs like Elizabeth North, Hackham West and Morphett Vale were among the worst offenders for wet wipe-related blockages during this period.

“This provides a timely reminder for everyone to only flush the four Ps – pee, poo, (toilet) paper and proof the items are flushable,” Daniel said.

“Wet wipes, even some labelled ‘flushable’, do not break down like toilet paper and can easily clog up household pipes and our mains, so it’s important to check the label for proof that the product is certified and safe to flush.”

In addition to tree root and wet wipe sewer blockages, SA Water has seen a recent rise in odour complaints caused by dry gully traps, which are common features of residential plumbing.

Gully traps are external drains designed to prevent sewer odours escaping by maintaining a water seal. However, many are installed under outdoor taps and in newer homes may not be regularly flushed with water.

“The recent dry spell has caused more of these gully traps to dry out, allowing odours to escape,” Daniel said.

“We’re encouraging residents to regularly check their outdoor gully traps and top them up with water if they appear dry.

“While we have received customer complaints of this kind in previous years, it’s only became a noticeable trend in recent months, particularly in new development areas in Adelaide’s north.”

Thirty-five odour complaints were linked to dried gully traps in the past 12 months – a 75 per cent increase compared to the previous year.

Contact: Tara Miko

Phone: 0448951418

Email: tara.miko@sawater.com.au