Blocked rainwater drain – causes, fixes, and prevention
When your rainwater drain blocks, it usually doesn't start with a flood — it starts quietly.
A bit of standing water after rain. A gully that smells earthy. A slow swirl that never quite clears.
Most people don't notice until it overflows or floods their drive.
By that point, it's not just a blocked drain — it's a sign your surface water system isn't coping.
At ASL Limited, we've helped hundreds of homeowners and private-road owners clear and maintain rainwater drainage systems so they stay clean, safe, and free-flowing.
What causes a blocked rainwater drain?
A rainwater system is designed to handle clean water — not mud, moss, debris, or sewage, especially from the kitchen, indirectly or directly.
Over time, the wrong things get in and reduce the flow.
Common causes include:
- Leaves, moss, and roof grit from gutters overflowing, or down the downpipes
- Driveway silt and gravel collecting in gullies
- Tree roots entering through old joints or cracks
- Collapsed or misaligned pipes (often from vehicle weight or because of old clay drains)
- Silted soakaways that no longer absorb water properly
The quick fix (and why it's not always enough)
Many people try to rod or jet a blocked rainwater drain themselves. Sometimes that works — but only for a short while.
If the blockage is caused by silt, roots, or a partial collapse, water will soon back up again.
That's why we often carry out a CCTV survey after clearing the blockage – to check what's really going on underground.
Our professional teams use:
- High-pressure water jetting to clear gullies and pipes
- Root cutting heads where needed
- CCTV inspection cameras to confirm everything's clean and intact
That way, we fix the cause — not just the symptom.
Do / Don't: simple prevention tips
| ✅ Do | ❌ Don't |
|---|---|
| Keep gullies and grids clear of leaves and moss | Pour plaster or cement water, paint, or oil down outdoor drains |
| Have gutters cleaned at least once a year | Run heavy vehicles over manholes unless they're reinforced |
| Use downpipe filters or leaf guards if you have nearby trees | Ignore slow drainage after heavy rain |
| Book periodic gully cleaning (6–12 months) | Wait until a flood before calling for help |
Before and after example
When to call ASL
If you notice:
- Water pooling after rain
- Gullies overflowing or bubbling
- Smells around the driveway or patio
Then it's time for a professional look.
Our engineers can clear, inspect, and document your system so you know exactly what's been done — and what's next.
We handle both private drains and shared systems, including roads, courtyards, and driveways.
Call ASL Limited on 0800 181 684
Book your inspection or gully clean today
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