Top Causes of Blocked Stormwater Drains and How to Fix Them

Blocked stormwater drains can quickly become a hassle, leading to backyard flooding, property damage and even street puddles.
These drains are designed to carry rainwater away from homes and buildings, keeping everything dry and safe. But when they get clogged − whether from fallen leaves, tree roots, or unexpected debris − water starts backing up, and that’s when problems arise.
Understanding what typically blocks stormwater drains can help you take proactive steps to prevent it from happening in the first place.
In this blog, we’ll explore the top causes of clogged stormwater drains, common warning signs to look out for, and practical solutions to keep your drains flowing smoothly. With a few preventative measures, you can avoid costly repairs and protect your home from water damage.
Common Causes of Blocked Stormwater Drains
Blocked stormwater drains can lead to pooling water, property damage, and costly repairs. Here are the most common culprits behind these frustrating clogs:
- Leaves and natural debris: Especially in autumn, leaves, twigs, and other organic materials can gather in drains, forming dense clogs that restrict water flow. Over time, this natural debris can also decompose, making it stickier and harder to remove.
- Tree roots: Tree roots naturally seek out water sources and can infiltrate tiny cracks in pipes. Once inside, roots grow and expand, completely blocking or even breaking the drainpipes.
- Sediment and mud: Stormwater runoff often carries mud, sand, and small stones into the drain. These particles can accumulate and solidify, particularly in areas with loose soil, reducing the capacity of your drainage system.
- Improper pipe installation: If pipes are poorly installed or incorrectly sloped, water flow can slow down, causing blockages. Over time, even a small installation error can lead to more frequent clogs.
- Foreign objects and litter: Items like plastic bottles, toys or garden waste can accidentally enter stormwater drains, obstructing water flow and causing backups.
Understanding these common causes can help you spot and prevent potential issues, keeping your stormwater drains flowing smoothly year-round.
Signs Your Stormwater Drain May Be Blocked
Noticing a blocked stormwater drain early can save you time, money and hassle. While stormwater drains are often out of sight, there are telltale signs that something may be clogging the flow.
One of the first indicators is water pooling around the drain area after heavy rainfall. If rainwater isn’t disappearing as quickly as it should, this could mean a blockage is slowing things down.
Another sign to watch for is water gurgling sounds from nearby gutters, downpipes, or drains. This noise happens when water struggles to pass through a partially blocked pipe, creating air pockets that make a gurgling sound. Additionally, strange odours around your drains or in your yard can suggest trapped debris is starting to decompose in the pipes.
For more severe blockages, you might see water backing up in places it shouldn’t − like driveways, lawns or even nearby roads. Left unattended, blocked stormwater drains can also lead to cracks in walls and floors due to the pressure buildup.
Recognising these signs early on gives you a chance to tackle the issue before it escalates, ensuring your drains stay clear and your property remains safe from water damage.
How to Unblock Your Stormwater Drain: Step-by-Step
Unblocking a stormwater drain doesn’t have to be daunting. Here are some straightforward steps you can take to get your drain flowing smoothly again:
- Remove surface debris: Start by clearing leaves, twigs and visible debris from around the drain. Often, surface build up can be the main culprit, especially after heavy rain.
- Use a high-pressure hose: Attach a high-pressure hose to flush out minor blockages in the pipe. This method can be particularly effective for clearing out mud and sediment build up. Insert the hose directly into the drain and run it on high for a few minutes to see if water flow improves.
- Try a drain snake: For deeper clogs, a drain snake (or plumbing auger) can be helpful. Insert it into the drain, twisting as you push forward. This tool breaks up blockages and allows water to pass through more freely.
- Apply drain cleaning solutions: For stubborn clogs, a chemical drain cleaner can help dissolve buildup. Use these products carefully, following all instructions, as they can sometimes damage older pipes.
- Call a professional for serious blockages: If tree roots or large obstructions are causing the blockage, it’s best to consult a plumber. Professionals have specialised equipment to clear severe blockages without damaging your pipes.
These steps can help you address minor clogs and keep your stormwater drain system functioning properly.
Preventative Measures to Avoid Future Blockages
Keeping stormwater drains clear is much easier with a few preventative steps. Start by regularly clearing leaves, twigs and other debris from your gutters and drains, especially after heavy storms or during fall when trees shed more leaves.
A quick clean-up can prevent this natural build up from accumulating and forming blockages over time. Installing mesh gutter guards can also help keep leaves and smaller debris out while allowing rainwater to pass through freely.
If you have trees close to your drainpipes, be mindful of their roots. Tree roots can grow into pipes searching for water, causing significant blockages. Regular maintenance or occasional professional root inspections can help catch these issues before they become bigger problems.
In areas prone to muddy runoff, such as near garden beds, consider installing a sediment trap. These traps catch mud and sand before it enters the drainage system, reducing the risk of clogging.
Also, avoid pouring oils, paints or harsh chemicals down outdoor drains, as these can coat pipes and attract debris. By taking these proactive steps, you’ll reduce the chances of costly and inconvenient drain blockages, keeping your stormwater system flowing smoothly all year round.
Time to Take Action
Keeping stormwater drains clear is key to avoiding backyard flooding, property damage, and costly repairs. Blockages often happen due to natural debris, tree roots and sediment build up, but with a bit of regular maintenance, you can keep issues at bay.
Simple habits, like clearing away leaves and checking for early signs of blockage, go a long way in keeping your drainage system flowing smoothly. If you notice unusual gurgling sounds, pooling water or unpleasant odours around your drain, it’s time to take action.
Many minor clogs can be fixed with basic tools, but don’t hesitate to call in a professional plumber for serious blockages, especially those involving tree roots. By staying proactive, you’ll protect your property and keep your stormwater drains in top shape year-round.
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