What Causes Blocked Drains and When Should You Call a Plumber?
Signs and Common Causes of Blocked Drains
Common Signs of a Blocked Drain
A complete blockage is usually obvious, but many drainage problems develop gradually. Identifying the early signs of a blocked drain can help prevent an overflow or more disruptive drainage problem.
Common warning signs include:
- Water draining more slowly than usual
- Gurgling sounds from sinks, toilets or floor wastes
- Unpleasant smells coming from drains
- Water rising in a nearby fixture when another is used
- A toilet that does not clear normally
- Repeated blockages in the same sink, shower or external drain
- Water or wastewater overflowing from an external access point
- Damp ground or pooling near a drainage line
One symptom does not always confirm the cause. A slow sink may have a blockage close to the fixture, while gurgling or slow drainage across several areas can indicate a restriction further along the drainage system.
Hair, Soap and Personal-Care Products
Bathroom drains regularly collect hair, soap residue and product build-up. Over time, this material can narrow the available opening inside the waste and catch additional debris passing through the drain.
A removable waste grate or strainer can help reduce the amount of hair and material entering the drainage system, but it will not prevent every blockage. If a shower or basin repeatedly drains slowly after accessible debris has been removed, further investigation may be required.
Grease, Fat and Food Waste
Cooking grease, oils and food residue can build up inside kitchen drainage. Even fats that enter the sink as a liquid can cool and harden further along the pipework, restricting the internal diameter of the drain.
Fats and oils should be allowed to cool and disposed of appropriately rather than being washed down the sink. Removing food scraps before rinsing dishes and cookware can also help reduce avoidable kitchen drain blockages.
Wipes and Other Unsuitable Items
Many products do not break down in drainage systems in the same way as toilet paper. Wipes, sanitary products, paper towel and other foreign objects can become lodged within toilet connections or sewer drainage.
Products labelled as flushable may still contribute to blockages depending on the product, pipework and wider drainage system. A practical rule is to flush only toilet paper and human waste.
Tree Roots in Underground Drains
Tree roots can enter underground drainage through cracks, failed joints or damaged sections of pipework. Once roots enter the drain, they can continue to grow and catch waste moving through the pipe.
Clearing the immediate obstruction may restore drainage flow, but recurring root-related blockages can indicate that the affected section of pipe also requires repair or replacement.
Damaged or Displaced Drainage Pipework
Older drainage systems, ground movement, construction activity and previous installation issues can cause pipes to crack, collapse or move out of alignment. Damaged pipework can restrict flow and create points where waste repeatedly collects.
Where the drain and available access points are suitable, a CCTV drain inspection can help identify the condition and location of damaged or displaced pipework.
Construction Debris and Sediment
Sand, grout, cement residue, soil and other construction debris can enter drainage systems during building, renovation or landscaping works. These materials may settle within the pipe and gradually create a restriction that becomes worse over time.
Stormwater Drain Blockages
Leaves, soil, roof debris and sediment can affect stormwater drains, grates and downpipe connections. Stormwater drainage problems are often noticed during periods of heavy rain when water cannot move away from the property quickly enough.
When to Call a Plumber for a Blocked Drain
Why Does the Same Drain Keep Blocking?
A recurring blocked drain often indicates that the immediate obstruction has been cleared without fully resolving the underlying reason it developed.
Possible causes of recurring drain blockages include:
- Damaged or deteriorated pipework
- Tree root intrusion
- Inadequate drainage fall
- Ongoing disposal of unsuitable material
- A partially cleared obstruction
- A fixture or waste connection that is not performing correctly
- Heavy usage in a commercial, strata or shared environment
If a drain repeatedly blocks, tell the plumber about its history. Information such as how often the blockage occurs, which fixtures are affected and what work has previously been completed can help determine whether a CCTV drain inspection or another form of investigation is appropriate.
Can You Clear a Blocked Drain Yourself?
Minor visible debris may sometimes be removed from an accessible waste grate without dismantling the plumbing. Beyond simple cleaning, care should be taken to avoid causing additional damage or creating a safety risk.
Avoid repeatedly using strong chemical drain cleaners. These products may not reach or remove the actual cause of the blockage, can create a hazard for a plumber who later works on the drain and may affect some types of pipework or fittings.
Do not insert makeshift tools into the drain if they could become stuck or damage the pipework. If wastewater is overflowing, several fixtures are affected or the blockage appears to be within underground drainage, professional assistance is the safer option.
What Should You Do While Waiting for a Plumber?
If you are waiting for a plumber to investigate a blocked drain, reducing further water use can help limit the risk of additional overflow.
- Stop using fixtures that cause the water level to rise
- Keep children, customers and pets away from wastewater
- Do not mix chemical cleaning products
- Move belongings away from the affected area where it is safe to do so
- Take photographs of the overflow or affected fixtures
- Note which fixtures are involved
- Tell the plumber whether the property has experienced similar drainage problems before
If the issue is actively causing property damage and the relevant water supply can be safely isolated, turn it off. Do not enter contaminated areas or attempt to access confined drainage spaces.
When Should You Call a Blocked Drain Plumber?
Professional blocked drain assistance should be arranged when:
- Wastewater is overflowing
- A toilet cannot be used normally
- More than one fixture is affected
- The blockage returns after previous clearing
- There is a strong sewer smell
- An external drain is overflowing
- You suspect tree roots or damaged underground pipework
- Water is pooling around the property during rain
- The drainage issue is disrupting business operations
- You are unsure whether the problem involves sewer or stormwater drainage
Prompt investigation can help reduce the risk of further overflow, hygiene concerns and damage to surrounding areas.
Blocked Drain Investigation and Prevention
How Does a Plumber Investigate a Blocked Drain?
A plumber will usually begin by identifying which fixtures are affected, when the drainage problem started and whether the blockage has occurred previously.
Accessible drainage points can then be inspected and an appropriate clearing or testing method selected based on the location and likely cause of the blockage.
Where drainage problems are recurring or damaged pipework is suspected, a CCTV drain inspection may be recommended. A suitable drainage camera can help identify issues such as:
- Foreign objects or internal obstructions
- Tree root intrusion
- Cracked or damaged pipework
- Displaced pipe joints
- Areas of deterioration
- Sections where waste is repeatedly collecting
The findings can then be used to determine whether further drain cleaning, servicing, repair or replacement should be considered.
How to Reduce Future Drain Blockages
Not every drainage problem can be prevented, particularly where underground pipework is damaged, but good plumbing habits can reduce avoidable blockages.
- Keep grease, fats and food waste out of kitchen drains
- Use suitable drain strainers where practical
- Flush only toilet paper and human waste
- Remove accessible hair and debris from bathroom wastes regularly
- Keep external grates clear of leaves, soil and other debris
- Arrange further investigation when the same drain repeatedly slows or blocks
- Keep records of previous drainage repairs and CCTV inspection findings
Recurring drainage problems should not be treated as normal. If the same area continues to block, identifying the underlying cause can help determine whether the drainage system requires more than routine clearing.
Need Help With a Blocked Drain?
Driftline Plumbing Services provides blocked drain, drainage and CCTV inspection services for homes, businesses and properties across Perth and Western Australia.
If your drains are slow, overflowing, producing unpleasant smells or repeatedly blocking, contact Driftline Plumbing Services to arrange an assessment and determine the most practical next step.