Think you’ve seen all the possible causes of blocked drains under the sun? Think again. No matter how many you’ve seen, we guarantee you we’ve not only seen more, but successfully dealt with each and every one of them, too!
This is Brisbane Drain Cleaning’s ultimate list – absolutely the most comprehensive breakdown of what’s really clogging up your pipes. From the expected to the unexpected, and across kitchens, bathrooms, outdoors, and even underground, we’ve really got it all.
If you’re sick of vague advice or half-lists that leave you guessing, this one’s for you. We’ve cleared drains all over Brisbane, and we’ve seen and solved every single one of these causes firsthand.
Let’s get started, because this is going to take a while:
The common indoor causes
We’ll start with the everyday culprits. These are the most common causes of blocked drains in kitchens, bathrooms, and laundry rooms – and they’re often pretty avoidable.
1. Food scraps down the kitchen sink
Even with a strainer, small food bits like rice, pasta, and veggie peels sneak through – and they swell with water. The result is a gurgling or completely blocked sink drain.
2. Grease and cooking oils
One of the biggest culprits. Liquid when hot, solid when cool – coating pipes and catching other debris.
3. Coffee grounds
They clump together like cement and settle deep in the u-bend.
4. Soap scum buildup
Bar soap in particular creates a thick residue over time, especially in bathroom drains.
5. Hair clogs
Hair binds with soap to form solid clumps. Shower drains, bath, and bathroom basin drains are the worst offenders.
6. Toilet paper overload
Even the most flushable of loo paper can block pipes if used excessively. Anyone with kids will experience a blocked toilet due to too much paper being flushed.
7. ‘Flushable’ wipes
Spoiler: they’re not flushable. They don’t break down and can choke up your toilet or even cause main sewer backups.
8. Cotton products
Cotton buds, pads, and makeup wipes absorb water and expand, creating serious blockages.
9. Dental floss
It wraps around other items in the drain and creates tangled, rope-like obstructions.
10. Children’s toys
Yes, it happens – small toys flushed ‘just for fun’ can jam toilets or pipes fast.
11. Sanitary products
Tampons and pads don’t belong in the loo. They’re absorbent, bulky, and don’t break down in water.
12. Paper towels and tissues
They’re made to stay strong when wet, which is why they jam pipes easily.
13. Broken or poorly installed pipework
DIY installations or ageing plumbing with collapsed sections can trap debris over time.
14. Old soap bar remnants
Ever notice old chunks slipping into the drain? They can sit and harden deep inside pipework.
15. Shampoo bottle seals or labels
Small plastic films can wash off bottles and lodge in pipe bends.
Bathroom & laundry drain issues
Beyond the basics above, your bathroom and laundry areas bring their own unique plumbing hazards. These are less obvious than food and hair – but just as likely to cause drain trouble.
16. Hair ties and bobby pins
Dropped into the sink or shower, these catch other material and create obstructions over time.
17. Excess detergent or washing powder
Too much soap can cause foamy buildup and scum that narrows the pipe passage.
18. Fabric lint
Especially from older washing machines without lint filters. It clumps up like wet paper mache.
19. Bathroom grime and mineral scale
Hard water leaves behind calcium deposits, especially in older homes.
20. Lost jewellery
Rings and earrings can fall through drains and become anchor points for other blockages.
Outdoor drain causes
As we all know – when it rains in Brisbane, it really pours. And outdoor drains bear the brunt. These causes mostly relate to stormwater drains, driveways, patios, and roof runoff systems.
21. Tree roots
They’re probably the number 1 long-term outdoor drain killer. Roots crack into pipes in search of moisture and take over fast.
22. Leaf litter and garden debris
Blown into stormwater grates and downpipes, they quickly clog narrow sections.
23. Mud and sediment buildup
Common after heavy rains – especially if landscaping is poor or there’s erosion.
24. Grass clippings
Washed in after mowing the lawn or during storms, especially around patios and driveways.
25. Garden mulch and bark
Lightweight and floaty – easily flushed into grates where it mats up.
26. Plastic bags and rubbish
One of the common culprits of blocked stormwater drains is street litter, which gets jammed in pits and pipes.
27. Outdoor toys or balls
Lost items like tennis balls or water guns can block grates and downstream stormwater systems.
28. Pet fur
Washing dogs outdoors or in the laundry? All that loose hair ends up down the drain.
29. Sand and gravel
From garden beds, construction runoff, or even backyard play – they settle heavily and reduce flow.
Structural & mechanical causes
Not all blockages are caused by what’s flushed or dropped in. Some are due to the way your pipes were installed – or what’s happened to them over time.
30. Pipe misalignment
Especially at joins between old clay pipes and newer PVC. Misaligned joints trap debris and restrict flow.
31. Pipe collapse
Often in ageing infrastructure, or after soil movement. This restricts flow entirely, causing backlogs.
32. Sagging or ‘belly’ in pipes
Low spots in long pipe runs collect water and waste, which can stagnate and block.
33. Incorrect gradient (slope)
If pipes aren’t laid at the right angle, waste doesn’t flow – it builds up.
34. Corrosion inside metal pipes
Over time, rust creates rough internal surfaces where matter gets caught and builds up.
35. Foreign object from construction
Cement, plaster, or insulation foam washed or dropped into drains during renovations or builds.
36. Tree debris from new developments
Clearing lots for construction can flush years of mulch and organic matter into old pipes.
Roof & stormwater drain specific
Your gutters and roof drainage systems have unique enemies – and when those blockages strike, they can cause internal leaks, overflows, or foundation damage.
37. Roof tile fragments
During storms or ageing, chipped tile pieces can fall into roof gutters and downpipes.
38. Bird nests in gutters
Common under eaves and downpipes. They block flow and cause overflow during rain.
39. Dead rodents or possums
Grim, but not uncommon. These can lodge in roof drainage and cause nasty odours and backups.
40. Rust flakes from old gutters
Corroded metal gutters shed flakes that collect in downpipes or grates.
Less obvious but real causes
Now for the wildcards – these aren’t the most common issues, but they’re all still real and can sneak up on any homeowner.
41. Grease from outdoor BBQ areas
Washing utensils and trays outdoors? That grease ends up where it shouldn’t.
42. Concrete or tiling slurry runoff
Leftover tiling or concrete works near outdoor drains can harden inside the system.
43. Natural disasters or flash flooding
Massive surges of water carry debris, soil, and household waste directly into stormwater networks, overloading or blocking them entirely. If your stormwater drains aren’t able to cope, this can be a serious problem with with Brisbane’s monsoon rains. That’s why it’s so important to have stormwater drainage designed for heavy flows.
Don’t let a blocked drain catch you off guard
Now you know the real causes of blocked drains – all 43 of them, in fact! Whether it’s garden clippings in the stormwater or grease in your kitchen sink, we’ve seen every single one. And we’ve cleared them all, too.
So next time water starts pooling or that awful gurgling starts up, don’t wait. Remember: the longer you leave a blockage, the worse it gets.
Need a drain expert in Brisbane?
Call Brisbane Drain Cleaning today for fixed-price drain clearing, fast quotes, and guaranteed workmanship across Brisbane Northside, Brisbane Southside, Logan, Moreton Bay and beyond. We get your drains sorted fast – no matter what’s got it clogged.
