Sydney’s Drainage Network Is One of the Longest in the World, and Much of It Is Over 70 Years Old
Sydney Water operates 24,346 kilometres of wastewater pipes in Greater Sydney. The amount of pipe is sufficient to reach from Sydney to London and back more than halfway. The network is connected to 682 wastewater pumping stations, and provides service to millions of properties from the Blue Mountains to the coast. An amazing piece of infrastructure, and much of this built decades ago, before the loads that are placed on it now.
Sydney’s earliest sewerage was built in the 1880s when open channels of stormwater were built to eliminate the inner-city creeks that emptied into the harbour. That was the time the Bondi ocean outfall sewer was constructed and remains in use to collect raw sewage that was previously freely discharging into Sydney Harbour. By the 1950s and 1960s the majority of the drainage infrastructure in the suburbs of Greater Sydney had been completed. The common material used was terracotta pipes with cement-mortared joints. The pipes are now 60-70 years old and are transporting loads for which they were not designed.
Add to this the fact that Sydney Water is having to clear around 20,000 blockages from its network each year and spend up to $27 million on the task, each year. Those main sewers under public land are theirs. The blockage of private pipes (from the house to the boundary) is your responsibility. Those private pipes are often the oldest, least maintained and most vulnerable part of the system.
We remove clogged drains in all Sydney suburbs. We know what’s underground, from the heritage terracotta pipes of the Eastern Suburbs, to the clay and PVC systems of Western Sydney, the steep sandstone of the North Shore to the flat floodplains of the Georges River catchment.
Sydney’s Blocked Drain Problem: The Numbers
One of the world’s longest sewer reticulation systems, these wastewater pipes are found throughout Greater Sydney.
Clearance of blockages from Sydney Water’s network per year. Any blockage on the private side of the boundary is yours.
According to Sydney Water’s own published data, this is the share of wastewater blockages caused by non-flushable wet wipes.
Spent annually by Sydney Water clearing blockages from their network. A homeowner posted $16,000 as replacement costs for the damage to his home’s private pipes caused by wet wipes.
Data from Sydney Water Corporation, Sydney Water wastewater blockages and Sydney Water IoT monitoring reports.
What Actually Blocks Drains Across Sydney
Sydney has regular patterns of drain blockage based on the age of the suburb, pipe material, the tree canopy, and housing density. Below are the six most prevalent causes that we see.
Tree Root Intrusion
The major contributor to the significant sewerage blockages in mature Sydney neighbourhoods. Root systems of Moreton Bay figs, Port Jackson figs, jacarandas, liquidambars and mature eucalypts extend 20-30 metres to find water. They easily find terracotta sewer pipes, which are joined by cement-mortared joints spaced about 1 metre apart. Sydney Water has seen cases of regrowth within a full access chamber after 11 months since jetting, even though the entry points were left uncovered.
Wet Wipes and Non-Flushables
According to Sydney Water, the leading cause of sewer blockages is non-flushable wet wipes, which account for 75 per cent of them. The wipes do not disintegrate as toilet paper does. They mix with grease and other waste materials to create thick plugs in the main sewers, sometimes hundreds of kilograms of “fatbergs”. Wet wipes build up at every turn in the sewer stack until the sewer backs up into the ground floor apartments where there are shared sewer stacks.
Grease, Oil and Fat
Cooking oil will flow down the drain when hot, solidifying on cooling. It sticks to the pipe surface, slowly causes narrowing of the bore each month, and is what wet wipes and debris stick to on the inside of the pipe. When fifteen or twenty kitchens are connected to the same drainage stack, as in an apartment building, grease accumulates far more rapidly than it would with a single kitchen. Every week we unclog grease-clogged kitchen drains all over Sydney, especially in the high density suburbs and hospitality precincts.
Ageing Terracotta and Clay Pipes
Sewer pipes in suburban Sydney were installed in terracotta from the 1940’s to 1970’s. Those pipes are 50 to 80 years old, much older than their design life! Joints crack. Sections settle. Cement mortar between 1 metre lengths of pipes gets broken. When each of these joints is compromised they allow access to roots, soil and groundwater. Terracotta pipes dating back to the early 1900’s are still in use in parts of the North Shore, older areas of the Eastern Suburbs and in the inner west.
Stormwater Overload
The stormwater system for Sydney Water provides services to around 645,000 properties in Greater Sydney. The stormwater network is stressed during periods of heavy rainfall, especially during east coast lows where 50mm of rain is received in an hour. When the storm hits, the blockage of the partial stormwater drains results in flooding. Suburbs in low lying flood catchments (Rushcutters Bay, parts of Marrickville, Canterbury and Rockdale) are especially susceptible to stormwater surge during heavy rain.
Construction Debris and Ground Disturbance
Sydney is in a constant state of construction. The construction of major infrastructure projects such as the Metro, WestConnex and hospital redevelopments, along with the constant re-development of residential properties, disrupt pipes in dozens of suburbs at the same time. Existing pipe joints are susceptible to damage by heavy machinery, excavation, and vibration stresses, which can shift pipe alignments that have held for decades. More drain blockages have been reported in suburbs close to large construction sites.
Drain Profiles Across Sydney’s Regions
The character of the drainage in each area of Sydney varies. The materials used to build pipes, the ground topography, the trees, and the density of houses differ from region to region as do the patterns of blockages.
Heritage Pipes, Harbour Salt, and Centennial Park Roots
Some of the oldest Sydney residential plumbing is found in the Eastern Suburbs. Victorian terraces, Federation semis and art deco apartments are built on the top of terracotta and earthenware sewer piping which dates back to the 1880s in some areas. The root systems of the 189ha of Moreton Bay figs and Port Jackson figs in Centennial Park extend deep into nearby residential streets. Exposed metal fittings and drain grates corrode much faster in the harbour area than in the suburbs.
Common cause: Tree roots through heritage era pipe joints. Recurrent obstructions within 6 to 18 months of unclogging (without relining).
Federation Terraces on Narrow Lots With Mature Canopy
Rows of Federation terraced houses on narrow blocks, with mature street trees planted in the 1920s and 1930s, run through Marrickville, Newtown, Enmore, Petersham and Stanmore. Sewer lines are located in confined backyards, especially under any extension to housing which may be under verandahs. Restricted access and old pipes. The streets are overgrown with fig trees, jacaranda and liquidambars which take over sewer lines.
Common cause: Root intrusion exacerbated by limited access. Buildup of grease from the location of restaurants and takeout places in hospitality strips such as King Street and Enmore Road.
Sandstone Terrain, Steep Grades, and Established Gardens
The Lower and Upper North Shore, Mosman, Cremorne, Lane Cove, Killara, Gordon is made up of sandstone land with steep gradients, which sewerage systems must cross. Decades of movement of the ground can alter the alignment of pipes over sandstone. Older trees will have established roots in all spaces available, including in some cases, pre-built gardens before the sewer lines were installed. Landscaping and heritage gardens are of high quality, and the no-dig relining is the preferred repair option.
Common cause: Movement of the ground in the form of sandstone has caused sections of pipe to be displaced. Garden plants penetrating the roots. Sites that are steep and have gravity-fed drains that are losing grade.
Clay Soil Movement and Rapid Densification
The western suburbs of Sydney, including Parramatta, Blacktown and Penrith, are constructed on a reactive clay soil which expands when wet and contracts when dry. The movement is seasonal, causing stress in the pipes as they open and dry up during certain times of the year and close and bulge during others. Western Sydney is also seeing high-density developments, subdivisions, dual occupancies and apartment developments, placing increased pressure on drainage infrastructure traditionally designed to serve lower-density housing.
Common cause: Clay soil cracking and displacing pipe joints. Addition to aging infrastructure due to urbanization and densification.
Sandy Soil, Established Trees, and Coastal Exposure
The Shire, Cronulla, Miranda, Caringbah, Engadine is on sandy land which enables roots to spread quickly and widely. Roots aggressively seek out sewer line moisture in the buffer zones of established eucalypts and paperbarks near the national park. Copper or brass fittings are subject to corrosion by sea salt in coastal neighborhoods. The sandy loam is easy to trench, but it is just as easy for roots to push through, so root intrusion is one of the top reasons for blockages in the Shire.
Common cause: The aggressive root intrusion via permeable sand. Corrosion of coastal fittings due to salt. Sand and leaf blockage of stormwater.
Shared Stacks, Shared Problems, Shared Costs
Sydney is one of Australia’s most densely populated cities with apartments. Apartment buildings account for 60-100 per cent of all dwellings in inner city suburbs. All apartment house buildings are equipped with common vertical sewer stacks that remove sanitary sewer discharges from all apartments on all floors. Ground-floor units are generally the hardest hit when a build-up of wet wipes and grease blocks the stack. Unlike houses, there are additional elements of responsibility, insurance allocation and cost-sharing.
Shared concern: Wet wipe and grease build-up in shared sewer stacks. Back-up of blockages at ground level due to blockages above.
Six Signs a Blocked Drain Is Building
In most cases a blockage does not occur in one day, but over time, usually weeks or months, before it fails all together. Spotting these early saves money and avoids the overflow that spoils a weekend.
Multiple Fixtures Draining Slowly
If all of the kitchen, shower and basin drains are slow, the issue is downstream in the main sewer instead of any particular fixture. The greater number of fixtures that are affected, the more severe the blockage.
Gurgling Between Drains
Flush the toilet and the shower drain bubbles. Run the dishwasher and the kitchen sink gurgles. When there is a partial blockage, the air in the system behind the blockage is forced through the closest water seal. One of the first and most consistent signs.
Foul Smell From Drains or the Yard
Rotten egg gas is created when waste sits behind the partially blocked pipe. If the odor is closest to an outdoor grate or from the laundry floor drain, the blockage is in the main sewer line that connects the house to the boundary.
Unusually Green Patch in the Lawn
Any crack in a buried sewer pipe acts as a slow-release fertilizer. If one area of the garden is greener and softer than the rest, especially along the likely path of the sewer line, the pipe is probably damaged.
One Fixture Backs Up Into Another
You flush the toilet and water comes up in the shower. You run the washing machine and water comes up through the laundry floor drain. Fixtures that are connected to each other are connected to a common drain line that is clogged downstream. The final phase prior to complete sewage flooding.
Overflow at the External Grate
The main sewer line is blocked if there is dirty water or sewage pooling around the overflow relief gully in the yard, particularly near the property boundary. All the line must be cleared before the situation gets inside the house.
How We Clear and Repair Drains Across Sydney
📹 CCTV Drain Camera Inspection
We send a camera down the pipe first before we clear anything. The live feed can illustrate in real time what is causing the blockage, roots, grease, wet wipes, displaced pipe, foreign objects, and where it is located. It can be difficult to distinguish between the various types of pipes in the city, from earthenware of the 1880s to PVC pipes today, and when you know what you’re dealing with, there’s no wasted effort. The video is captured and provided to you, your strata manager or your insurer.
💦 High-Pressure Jet Blasting
A highly concentrated water jet, capable of up to 5,000 PSI, removes root masses, grease, accumulated wet wipes and sediment. Jetting creates a wide opening through the pipe instead of the narrow one a drain snake makes, which restores full flow. Jetting will clear the blockage on the same appointment for most blockages at houses, apartments and commercial properties throughout Sydney. A second camera pass is confirmed prior to leaving.
🔧 Pipe Relining (No-Dig Repair)
If the camera is able to see cracks in the joints, root entry holes, or corrosion damage, relining forms a new pipe inside the old pipe, eliminating the need to replace the pipe. No digging. No destroying driveways, gardens, or landscaping. Inflated against the pipe wall, the resin liner is cured in place from an existing access location. If there are no joints, there won’t be any more root entry in the future. The warranties for most relining products are 35 to 50 years. For a city as rich in heritage gardens and high quality landscapes as Sydney, relining is sometimes the only viable solution.
⛏️ Excavation and Replacement
If the pipe is completely destroyed, out of alignment, or broken in several places, the damaged pipe must be removed. We dig up, replace with modern PVC on a properly designed slope and put back the surface. We don’t recommend it unless there is no alternative; it is more disruptive and expensive than relining. However, if the pipe can’t be salvaged, this is the only honest option.
How a Drain Call-Out Works
Let us know what is happening: slow drains, overflow, foul smell, flooding etc. A few questions will be asked and a plumber will be dispatched to your suburb.
We use a CCTV camera to go down the line to find the blockage, determine the cause of the blockage and determine the condition of the pipe. No guessing. No digging blind.
We restore full flow with jet blasting, mechanical clearing or a combination of both. Clear price before any work commences. We reaffirm with a second camera pass.
A written report is provided that includes video. If structural damage is discovered, we discuss options clearly with you (relining or excavation) along with their associated costs. We provide prevention tips for your situation, if it was only a matter of clearing.
What Our Customers Say
“Premium Sydney Plumbers was called to the back yard as our main yard drain was backing up and he got the job done quickly and efficiently, leaving the place spick and span and providing us with tips to prevent the problem from occurring again.”
“Called for enquiry call out and they arrived within 2 days, was reasonably priced for services and highly recommend for your plumbing needs.”
“Callout was very quick, very good service, highly recommend, thank you.”
Blocked Drains Sydney: Frequently Asked Questions
Suburbs We Service Across Sydney
Unclog blocked drains from Eastern Suburbs, inner west, North Shore, western suburbs, southern suburbs and anywhere in between, in all of Greater Sydney.
Blocked Drain Anywhere in Sydney?
Don’t let it get worse! A slow drip today is an overflow tomorrow! Call us and we will sort it out, but of course at the price you agreed to, the same day!
