{"id":247797,"date":"2025-10-24T05:07:08","date_gmt":"2025-10-24T05:07:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/247797\/"},"modified":"2025-10-24T05:07:08","modified_gmt":"2025-10-24T05:07:08","slug":"secret-report-shows-likely-source-of-poo-balls-that-closed-sydneys-beaches-last-summer-pollution","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/247797\/","title":{"rendered":"Secret report shows likely source of \u2018poo balls\u2019 that closed Sydney\u2019s beaches last summer | Pollution"},"content":{"rendered":"

A secret report reveals the likely source of the fatberg balls that closed a raft of Sydney<\/a> beaches last summer \u2013 with most coming from the deepwater ocean outfalls at Malabar, Bondi and North Head.<\/p>\n

The partly-redacted scientific report, obtained by Guardian Australia under freedom of information laws, points to a combination of heavy rains and a buildup of fats, oils and greases as the likely cause of the \u201cpoo balls\u201d<\/a>.<\/p>\n

Authorities are unable to say when balls could wash up again \u2013 but are urgently working on solutions.<\/p>\n

\u201cWe do believe that fat is accumulating somewhere in the system. We know [it\u2019s] in the pipes, definitely, [but] we\u2019re unsure of its whereabouts specifically,\u201d Sydney Water\u2019s environment manager, Ben Armstrong, told Guardian Australia.<\/p>\n

The report notes that the debris balls \u201care assumed to be of a sewage origin\u201d and their \u201cdischarge is most likely to be from an outfall, but the stormwater system may also be implicated\u201d.<\/p>\n

\u201cFats, oils and greases (FOGs) in the sewerage system provide the \u2018stickiness\u2019 for the debris balls. They possibly adhere to the sides of pipes. Particulate material may then stick to these FOGs,\u201d the oceanographic modelling report by WQ Data states.<\/p>\n

\u201cHigh rainfall in the year or so leading up to the discharge of the debris balls effectively \u2018primes\u2019 the sewerage (or stormwater) system. Within a few days prior to their discharge, further rainfall is sufficient to move the combined FOGs and particles out of the pipes.\u201d<\/p>\n

Wave action then rolls the combined FOGs and particulate matter into balls. Between October 2024 and February 2025, \u201cthe oceanographic \/ meteorological conditions were suitable for the debris balls to be released and for them to be moved to the Sydney and NSW south coast beaches\u201d.<\/p>\n

Oceanographic modelling data prepared by WQ Data. Photograph: WQ Data Pty Ltd<\/p>\n

Work by Sydney Water and the NSW Environment Protection Authority (EPA) suggests the so-called fatbergs are due to an increased use of vegetable oils, which break down slowly, an increase in food outlets and the overall growth of the city\u2019s population.<\/p>\n

The EPA has previously said testing revealed the balls were consistent with human-generated waste such as grease and faecal matter.<\/p>\n

There are particular concerns about the Malabar sewage treatment plant.<\/p>\n

\u201cThere are global issues about fatbergs and sewers, and it\u2019s effectively the same thing,\u201d the chair of the EPA\u2019s advisory panel, and an independent expert, Prof Stuart Khan says.<\/p>\n

\u201cThis particular sewer [at Malabar] has had a long time for fats, oils and grease to build up.<\/p>\n

\u201cThere\u2019s nearly 2 million customers in that system and over the past 10 years, not only has there been growth in population using that system, but also increasing numbers of food outlets that may or may not have appropriate trade waste licenses in place or the right infrastructure in terms of grease traps and things to be preventing run off of fats, oils and grease.\u201d<\/p>\n

The release of the oceanographic report, commissioned by Sydney Water, suggests the state-owned corporation could have known as early as 3 February 2025 that the debris balls were likely from its ocean outfalls. That is the date of the \u201cpreliminary draft\u201d.<\/p>\n

Guardian Australia first reported in October 2024 that a team of scientists was investigating whether the balls could be linked to sewage<\/a> and whether they could have come from water treatment plants.<\/p>\n

The EPA chose to reveal the content<\/a> \u2013 but not the source \u2013 of the beach balls on the day of the US election in November.<\/p>\n

The EPA publicly confirmed their likely origin in April<\/a> 2025 when it issued a preliminary investigation notice to Sydney Water.<\/p>\n

Since then, the two agencies have been conducting urgent studies to ascertain the extent of the problem.<\/p>\n

Sydney\u2019s sewage system relies on three \u201cdeepwater ocean outfall\u201d pipes that run up to 4km out to sea at Malabar, Bondi and North Head. The sewage receives primary treatment to remove some solids and is then pumped through pipes, exiting through diffusers 60 metres below the surface, where the plume mixes with seawater.<\/p>\n

Treatment plants map<\/a><\/p>\n

Prior to 1990, Sydney\u2019s sewage was discharged from the bottom of the cliffs near the plants, just a few hundred metres out to sea. Pollution<\/a> was a regular phenomenon, particularly after rain, with faecal contamination and other rubbish regularly washing onto beaches.<\/p>\n

The ocean outfalls were highly successful in improving water quality,<\/a> with faecal contamination becoming almost negligible, except immediately after rain, when stormwater runoff sometimes caused an issue.<\/p>\n

But the growth in population, food outlets and industry, particularly in Sydney\u2019s west, is causing a buildup of fats, oils and greases in the system, which threatens to overwhelm it.<\/p>\n

The oceanographic study<\/p>\n

The study commissioned by Sydney Water, which mapped oceanographic currents and winds, traced the balls back to more than one of the three major sewage outfalls.<\/p>\n

It hypothesises that heavy rain about six months prior to the discharge of the balls, which occurred between October 2024 and January 2025, primed the system and further heavy rain then dislodged the fatbergs.<\/p>\n

\u201cNo single discharge from a single origin could be responsible for the appearance of the debris ball on all beaches between October 2024 and February 2025.<\/p>\n

\u201cTen (or perhaps more) discharge events may be responsible for the observed debris balls on the beaches during this period.\u201d<\/p>\n

skip past newsletter promotion<\/a><\/p>\n

Sign up to Breaking News Australia<\/p>\n

Get the most important news as it breaks<\/p>\n

Privacy Notice: Newsletters may contain information about charities, online ads, and content funded by outside parties. If you do not have an account, we will create a guest account for you on theguardian.com<\/a> to send you this newsletter. You can complete full registration at any time. For more information about how we use your data see our Privacy Policy<\/a>. We use Google reCaptcha to protect our website and the Google Privacy Policy<\/a> and Terms of Service<\/a> apply.<\/p>\n

The report studied 10 incidents. The first balls were found on Coogee beach in October 2024. Subsequent incidents occurred at other eastern suburbs beaches and Botany Bay, Manly, the northern beaches and on the south coast.<\/p>\n

The report and subsequent studies raise the question of whether Sydney Water\u2019s sewage system has reached its limits and whether debris balls will return to the beaches this summer if rainfall conditions are repeated.<\/p>\n

\u201cWe\u2019ve had rainfall events and pulses going through the system without having debris balls previously, to our knowledge,\u201d Khan says.<\/p>\n

\u201cSo we\u2019re trying to find out: why now? And why only sometimes now? Why not after every wet weather event? There are questions around whether the catchment to the sewer is changing, and therefore whether or not it\u2019s something that we\u2019re going to see more often. If that\u2019s the case, then better controls over what goes into the sewer will be important.\u201d<\/p>\n

Wastewater systems in greater Sydney. Illustration: Sydney Water<\/p>\n

There are concerns about what is lurking in the deepwater outfall pipes.<\/p>\n

Sydney Water can inspect other parts of the system, but is unable to inspect these pipes, which are 35 years old. To undertake maintenance would require decommissioning the outfalls and reverting to releasing barely treated sewage at Sydney\u2019s cliffs.<\/p>\n

The solution<\/p>\n

Armstrong says Sydney Water\u2019s \u201cSave our sinks\u201d campaign encourages businesses and households to avoid putting oils and fats, milk, coffee grounds and other solids down the sink.<\/p>\n

Changing consumer behaviour is an important part of the solution, he says. Maintenance is also crucial.<\/p>\n

Julian Thompson, operations manager at the Environmental Protection Authority, says Sydney Water has \u201ca fairly stringent\u201d maintenance program, particularly around the Malabar catchment.<\/p>\n

\u201cThey spend quite a lot of money on desilting their sewers. They have crews that can get into those pipes. It sounds like a pretty unpleasant job, but they\u2019re basically within those large pipes \u2026 taking out fats, oils and greases, taking out wet wipes and other things that block up sewers.\u201d<\/p>\n

The longer-term solutions require greater investment and some hard decisions for the NSW government.<\/p>\n

\u201cWhat we\u2019re currently doing now is not sustainable \u2013 discharging 80% of the sewage produced by 5 million people into the ocean after only primary treatment,\u201d Khan says. \u201cEvery drop of water we send out into the Pacific Ocean is wasted water.\u201d<\/p>\n

Sydney Water is looking to expand or build water resource recovery facilities<\/a> which take sewage, highly treat it and render it suitable for reuse. It has a demonstration plant at Quakers Hill.<\/p>\n

This could reduce pressure on the existing wastewater system while potentially providing Sydney with a non-rainfall-dependent form of additional drinking water.<\/p>\n

A map showing proposed new water treatment sites and Sydney Water\u2019s existing plants, which have deepwater outfall pipes that reach up to 4km off the coast.<\/a>A map showing proposed new water treatment sites and Sydney Water\u2019s existing plants, which have deepwater outfall pipes that reach up to 4km off the coast.<\/p>\n

\u201cThe NSW government made a very clear statement that we would only proceed with that if it could be demonstrated that there\u2019s a social license for it,\u201d Khan says.<\/p>\n

Sydney Water\u2019s long-term plan<\/a> has these projects listed with a 10-year horizon. They may need to be brought forward.<\/p>\n

The state\u2019s water minister, Rose Jackson, says: \u201cSydney Water is now working to prevent future events through new programs to help reduce the amount of fats, oils and grease entering the wastewater system.\u201d<\/p>\n

She noted the long-term plan to upgrade the system<\/a> and reduce the volume of water flowing through the outfalls.<\/p>\n

\u201cThis approach delivers environmental benefits while avoiding the significant cost to customers of upgrading coastal plants and pipelines to manage increasing flows,\u201d Jackson said.<\/p>\n

Mysterious debris balls that washed up in Sydney were examined by Prof Jon Beves and his team at UNSW. Photograph: Prof Jon Beves<\/p>\n","protected":false},"excerpt":{"rendered":"A secret report reveals the likely source of the fatberg balls that closed a raft of Sydney beaches…\n","protected":false},"author":2,"featured_media":247798,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47],"tags":[192,79],"class_list":{"0":"post-247797","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-environment","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/247797","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=247797"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/247797\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/247798"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=247797"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=247797"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=247797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}