Top 5 Causes of Blocked Drains and How to Avoid Them

Understanding what causes drain blockages helps you prevent them. Here are the five most common culprits we see every week.

1. Leaves and Garden Debris

Leaves, twigs, mulch and garden clippings are a leading cause of blocked stormwater drains, particularly during autumn and after storms. When debris accumulates over external drain grates, it prevents water from entering the stormwater system and causes surface flooding.

Prevention: Clear external drain grates regularly, especially during autumn. Install gutter guards. Keep garden beds and mulch away from drain openings.

2. Unexpected Items Flushed Down Toilets

Despite clear labelling, many items that should never enter a drain are flushed daily:

Prevention: Place a bin next to every toilet. Only flush human waste and toilet paper — nothing else.

3. Grease, Fat and Cooking Oil

Cooking oil and grease are liquid when hot but solidify as they cool inside your pipes. Over time, this creates a thick coating that narrows the pipe diameter and eventually blocks flow completely.

Prevention: Never pour cooking oil, fat or grease down the sink. Let it cool and solidify, then scrape into the bin. Wipe greasy pans with paper towel before washing.

4. Hair

Hair is one of the most common causes of slow-draining showers and basins. Individual strands combine with soap residue to form dense, tangled clogs that trap other debris.

Prevention: Install mesh drain strainers in all showers and basins. Clean them weekly. For existing slow drains, remove the strainer and pull out any visible hair accumulation.

5. Excessive Toilet Paper

While toilet paper is designed to break down in water, using excessive amounts in a single flush can overwhelm the system — particularly in older properties with narrower pipes.

Prevention: Use reasonable amounts and flush twice if necessary rather than overloading a single flush. If your toilet frequently blocks, it may indicate a partially obstructed sewer line that needs professional inspection.

Frequently Asked Questions

Are flushable wipes really safe to flush?

No. Despite labelling, flushable wipes do not break down like toilet paper and are a leading cause of sewer blockages.

Can I pour grease down the drain with hot water?

No. Hot water may keep grease liquid temporarily, but it solidifies further down the pipe. Always dispose of grease in the bin.

How often should I clean my drain strainers?

Weekly for showers and basins. Monthly for external stormwater grates, and weekly during autumn leaf-fall.

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