Thirty minutes later, Copeman takes us down a concrete tunnel to a rusty metal door in waist-high water. Beyond this so-called bulkhead door lies the fatberg in an \u201cinaccessible dead zone<\/a>\u201d.<\/p>\n Sydney Water staff make their way to the sedimentation tanks at the Malabar wastewater treatment plant. Photograph: Jessica Hromas\/The Guardian<\/p>\n Sydney Water doesn\u2019t know exactly how big the fatberg is. They\u2019ve tried to find out by sending a drone into the small space above the congealed fats, oils and grease (FOG) and below the concrete ceiling.<\/p>\n But it couldn\u2019t fly straight due to the turbulence created by sewer gases and the rapid flow of treated effluent to a deepwater ocean outfall (Doof) 2.3km out to sea.<\/p>\n The corporation\u2019s working theory is that parts of the fatberg are dislodged during rapid changes in pumping pressure. These \u201csloughing events\u201d have been caused in the past by a loss of power or heavy rainfall.<\/p>\n Sydney Water diagram showing the potential location of the fatberg. Illustration: Sydney Water<\/p>\n The dislodged pieces of fatberg are then forced through diffusers \u2013 enormous upturned shower heads which disperse effluent from the ocean floor \u2013 at the end of the outfall.<\/p>\n In late 2024 and early 2025, the poo balls were carried back to shore by waves and wind. A number of Sydney beaches were closed including Coogee, Bondi<\/a> and Manly<\/a>.<\/p>\n Sign up for the Breaking News Australia email<\/a><\/p>\n In February this year, the NSW Environment Protection Authority (EPA) issued a pollution reduction program<\/a> to Sydney Water \u201crequiring a range of significant works, including fat removal from the Malabar deep ocean outfall bulkhead area\u201d.<\/p>\n Affected beaches map<\/a>\u2018We\u2019ve tried to understand what it is\u2019<\/p>\n We visit the plant on the day the Artemis II moon mission launches. Clearing a fatberg seems a smaller step for humanity.<\/p>\n A five-metre-long area directly behind the brooding bulkhead door can be accessed at certain times. It ends at treated wooden stopboards that reach almost to the ceiling of the tunnel. The inaccessible fatberg is just past this point.<\/p>\n Fiona Copeman, the Malabar hub manager, at the bulkhead door. Photograph: Jessica Hromas\/The Guardian<\/p>\n At times of high flow, material constantly comes back over the gap above the stopboards, making it unsafe to open the bulkhead door.<\/p>\n But when the flow is lower, and there\u2019s a lunar low tide combined with minimal rainfall, crews can access this smaller chamber to remove some spillover, typically every four to six months.<\/p>\n Six people work to pump out the rainwater that collects between the door and the stopboard. They pop open the hatch, not the entire door, and insert a hose that allows two hours worth of fatberg to be pumped out.<\/p>\n Above ground, we are shown the easier option. A gas vent can be opened up and a hose lowered down 20 metres to suck up the fat in front of the stopboards.<\/p>\n Most of the problematic material removed so far, including 53 tonnes in April 2025, has left this way. But more re-accumulates in its place and the \u201cfour-bus area\u201d beyond the stopboards remains undisturbed.<\/p>\n The Malabar wastewater treatment plant deals with 40% of Sydney\u2019s sewage. Photograph: Jessica Hromas\/The Guardian<\/p>\n Copeman has seen the accumulated FOGs at Malabar over almost 15 years. She says the consistency varies \u2013 sometimes it\u2019s gritty. Sometimes it\u2019s scummy.<\/p>\n \u201cWe\u2019re inquisitive people, so we\u2019ve put it in our hands and we have felt it,\u201d she says.<\/p>\n \u201cSometimes we\u2019ve seen if we can roll it into balls and thrown it around \u2013 and we\u2019ve tried to understand what it is.\u201d<\/p>\n Fiona Copeman. Photograph: Jessica Hromas\/The Guardian<\/p>\n What does it smell like? \u201cSewage,\u201d Copeman replies.<\/p>\n Sydney Water<\/a> says most of the outfall tunnel is unsafe for people to access.<\/p>\n The only way to access the fatberg, the corporation insists, is to shut down the city\u2019s largest ocean outfall for months and dump the primary-only treated sewage<\/a> at the cliff face. A secret August 2025 Sydney Water report obtained by Guardian Australia noted this had \u201cnever been done\u201d and was \u201cno longer considered an acceptable approach\u201d.<\/p>\n \u201cThe maintenance strategy when they put it [the deepwater ocean outfall] in, in the 90s, because everyone was used to [cliff] outfalls, was just take it offline, put the flow back on the cliff face, and maintain the tunnel,\u201d Copeman says.<\/p>\n Down at the bulkhead door, it is eerily odourless, but this is not the case in Sedimentation Room Area 4, in the primary treatment facility. As we step inside, the smell matures quickly from a seaside pong to a meaty fug which opens up the nostrils. It\u2019s a pandemonium of aromas so bad they seem to cancel each other out.<\/p>\n We are using hearing protection but none of the staff wears anything over their noses.<\/p>\n \u201cI reckon you\u2019re either built for sewage, or you\u2019re not,\u201d Copeman says.<\/p>\n Scum on the top of a sedimentation tank at the Malabar treatment plant. Photograph: Jessica Hromas\/The Guardian<\/p>\n In row upon row of sedimentation tanks, reflectionless water is flowing. It\u2019s black from ferric chloride used for odour control. The water moves so gently you can\u2019t tell until you spot tiny bubbles and fat particles speckling the surface like galaxies.<\/p>\n Slower is better: the more time water spends in a tank, the more solids sink to the scrapers at the bottom. This \u201csludge\u201d is removed for further treatment and then used on land, in the forestry industry, for example. The remaining liquid or \u201ceffluent\u201d is then sent out to sea.<\/p>\n Malabar\u2019s sedimentation tanks. Photograph: Jessica Hromas\/The GuardianBen Armstrong of Sydney Water in the tunnel leading down to the bulkhead door. Photograph: Jessica Hromas\/The Guardian<\/p>\n During dry weather, 485 megalitres \u2013 or 194 Olympic pools \u2013 of wastewater comes through the Malabar plant each day. That rises to 1,300 megalitres during wet weather. Higher volumes mean less time in the sedimentation tanks \u2013 and fewer solids being removed.<\/p>\n One of the sedimentation tanks has been emptied out so the scrapers can be upgraded as part of a pollution reduction program.<\/p>\n Copeman notes that the \u201cscum\u201d transfer pumps are also being improved. The FOGs on top of the sewage are sent to an onsite cogeneration plant, which typically powers 80% of Malabar\u2019s operations. On a good day the plant sends excess electricity to the grid.<\/p>\n These changes are in addition to $3bn of upgrades from Sydney Water\u2019s existing capital works program to plants upstream, which aim to divert the amount of sewage being treated at Malabar<\/a>. The plant currently deals with 40% of the city\u2019s waste.<\/p>\n A swimmer at Malabar beach. Photograph: Jessica Hromas\/The Guardian<\/p>\n FOGs in the Malabar catchment have reportedly risen by 39% over the past 10 years<\/a>. Sydney Water is now running a campaign<\/a> encouraging people not to put fats, oils and grease down sinks.<\/p>\n Ben Armstrong, the principal manager of environment at Sydney Water, says: \u201cWe\u2019re at the end of the pipe, so it\u2019s really hard when you\u2019re doing those volumes and loads to treat it when you really need to be removing it at the source.\u201d<\/p>\n The entrance to the Malabar facility. Photograph: Jessica Hromas\/The Guardian<\/p>\n At nearby Malabar beach on the day of our tour, swimmers dive into the water untroubled, as the occasional waft of sewage drifts over the cliffs.<\/p>\n After washing our hands, but before we leave the facility, Copeman shows photos of the headland before and after the Doof came online in the 1990s.<\/p>\n In the first picture, you can see the brown sewage plume advancing into the ocean from the cliffs. In the second, the sea is indigo.<\/p>\n![\"Staff](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/04\/Malabar_fatberg_number_1___loop--89a917e4-0c1b-4c79-86b0-c26b0d252ce0-1.0.0000000.jpg\")
Staff in the tunnel above the bulkhead door.<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/04\/Malabar_fatberg_loop_number_2___video--4635afc7-37ac-4169-bd0d-35547888cf82-1.0.0000000.jpg\")
The sedimentation tanks at the Malabar plant.<\/p>\n