How to Unblock an Outdoor Drain

Need help quickly?

Call ASL on 0800 181 684 – we’re happy to help.

Understanding Outdoor Drains: Surface Water vs Foul Water

Not all outdoor drains are the same, and this is something many homeowners don’t realise.

These drains carry sewage to the main foul sewer or a treatment system.

Sometimes we do find surface water connected to the foul drainage system, which should not normally happen unless in a combined sewer area. This is often a downpipe from the roof connecting into a foul kitchen gully. When heavy rain enters the sewage system, it can overload the pipes and contribute to blockages or flooding if not designed to handle the extra flow.

This is something we often discover during CCTV inspections

First signs your outdoor drain is blocking

Most outdoor drains give you warning signs before they completely block.

You might notice:

• Water sitting around the drain,
• Slow-draining water after rain,
• Bad smells near the drain,
• Gurgling sounds when water flows,
• Water rising in inspection chambers.

If you spot these signs early, the problem is usually quick to solve.

Step 1: Check the drain cover or gully

Many blockages happen right at the top of the gully drain.

Lift the drain cover carefully and look inside. You may find:

• Leaves and debris,
• Mud or silt,
• Food waste from kitchen gullies,
• Grease build-up,
• Foreign objects.

Often, the blockage is simply sitting on top and can be removed by hand or with a tool.
Gloves are a good idea here.

Step 2: Try flushing the drain

Once the visible debris is removed, pour a bucket of water into the drain.

If the water flows away quickly, the blockage may already be gone.

If the water drains slowly or sits there, the blockage is likely deeper inside the pipe.

Step 3: Use drain rods

Drain rods can be useful for pushing through a blockage further down the pipe.

Turn the rods clockwise as you push them forward. This helps break up debris and prevents the rods from unscrewing underground.

Common blockages you may clear with rods include:

• Mud and silt,
• Toilet paper build-up,
• Leaves,
• Small root masses.

However, rods should be used carefully. If the blockage is caused by a collapsed pipe or roots, rods may not solve the problem.

Step 4: Know when to stop

If the drain keeps blocking again and again, there is usually an underlying cause.

For example:

• Tree roots entering the pipe,
• Cracked or broken drains,
• Pipes that have sunk or moved,
• Foul water or rainwater entering the wrong system,
• Fat and grease build-up further down the line.

In these cases, the blockage is only a symptom of a bigger issue.

How professionals unblock outdoor drains

At ASL Limited, most blocked outdoor drains can be cleared in around 30 minutes using professional equipment, and we often do a quick look camera survey.

We typically use:

• High-pressure water jetting,
• Specialist rods and cutters,
• Root cutting tools,
• Vacuum equipment where necessary.

But the most important step happens after the drain is unblocked.

Our quick CCTV look

Whenever we unblock a drain, we usually carry out a quick CCTV camera check.

This is not a full drain survey – it’s simply a quick look to see if anything obvious caused the blockage.
In many cases, we find things like:

• Roots entering the pipe,
• Cracked pipes,
• Pipes that have dropped or moved, particularly at joints,
• Rainwater entering the foul system,
• Build-up of fat and debris.

This quick look helps prevent the drain from blocking again a few weeks later.

Customers really appreciate this because they know what caused the problem, not just that the water is flowing again.

A real example

Recently, we cleared an outdoor drain that had been blocking every few months.

Once the pipe was cleared, we ran a quick camera check and found a large root mass growing through a joint in the pipe.

Without the camera, the drain would have kept blocking.

Instead, we removed the roots and recommended a permanent repair.

Problem solved.

When to call a professional

It’s time to call a drainage specialist if:

• The drain keeps blocking,
• Water is backing up into the property,
• You can smell sewage outside,
• Drain rods are not clearing the blockage,
• Multiple drains are backing up at once.

These signs usually indicate a deeper drainage problem.

Final advice

Outdoor drains are part of the system that protects your property from flooding and damage. If you notice early warning signs, dealing with them quickly can save a lot of trouble later.

ASL’s highly experienced engineers work across Surrey and the surrounding counties, where many properties feature older drainage systems. Blocked drains, root ingress, and collapsed pipework are issues we encounter regularly. Whether we’re carrying out CCTV surveys or drain clearance work in rural market towns, leafy villages, or the kind of established residential streets where the infrastructure has simply been there for decades.

📞 Need help with a blocked outdoor drain?

Call ASL Limited on 0800 181 684

Our experienced engineers can usually clear the blockage quickly and inspect the pipe with our camera to ensure the problem doesn’t return.