How to Unblock an Outside Drain in 6 Easy Steps

By Lee Devlin, Director, Homecure Plumbers
Last updated 13 October 2026

Dealing with a blocked outside drain or overflowing gully on your property? Here’s how to clear it yourself, and when to call us.

Blocked drains can be frustrating. They create backlogs of waste and often result in rather unpleasant smells. Usually, you’ll get blockages in the narrower pipes of your home, such as those in sinks or toilets. However, debris can build up within outside drains as well, leading them to become clogged.

Often you can clear it yourself. These are the steps our London drainage engineers follow.

Step One: Assess the Problem

Access your outdoor drainage through whatever method you can. For most properties, this means removing the drain cover, which can help you identify any drain blockages. Use a proper pair of drain or manhole lifting keys. A screwdriver will just snap or chew up the slots on heavy cast iron or recessed inspection covers. Once you have access, inspect the problem.

Is the blockage near the surface or is it out of sight?

Is it simply gunk or does it appear to be a tougher job?

If, after assessing the problem, you think you can manage the job yourself, move on to step two. If the drain blocked issue looks to be far more challenging than you anticipated, we recommend you avoid tackling the problem yourself and move to step six on this list.

You may also find you have clogged gutter pipes, which are easier to clean out, although it is still worth following these same steps.

Step Two: Obtain the Appropriate Tools for the Job, Including a Drain Rod

Removal of an outdoor drain blockage requires a few things. The most critical tool is a drainage rod. Standard drain rods are flexible polypropylene rods that screw together with brass joints. They enable you to push through the blockage in your drain, reaching deep into the external systems. A drain rod can be manipulated to tackle various types of blockages by feeding it into the drain and twisting it to break apart stubborn obstructions. Cheap and easy to find, don’t try to unblock an outside drain without one.

You’ll also want some protective clothing, as you’ll be digging around inside the drain. We recommend waterproofs, gloves and long-sleeves, as well as protective gear for your mouth and eyes if the blockage is near the surface. Splatter can contain nasty sewage bacteria, which you don’t want to come into contact with, as it may cause illness or infection.

You’ll also need a bucket and hose, ideally, a pressure hose if you have access to one.

Step Three: Remove Any Blockages You Can Reach

Can you get your arm in and take out some of the blockage, including food waste? If so, this is your best chance of shifting the matter clogging your drains and making it easier to use your drainage rods for simple debris removal.

It’s a horrible job, but it’s worth it.

Grab your bucket, place it by the drain and dig in. Remove every piece of blockage material you can. The more you remove, the easier the next steps become.

Step Four: Clear the Blockage

Using your drainage rods, attempt to flush out the blockage.

The rods should slide through the sludge, though you may need to apply a bit of pressure. Move the rods around, breaking apart as much of the blockage as possible. This may take some time, especially if the buildup is quite large or stubborn, so be patient. Keep plunging until it becomes easy to move the drainage rods, if you can see the blockage, it will start to drain and dissipate.

When using your drainage rods, be sure to twist clockwise. If you twist anti-clockwise, you may find the tough blockages actually result in the joints of your rods becoming unscrewed!

Never force the rods if they jam, and always keep some tension on them, so they don’t snap or come apart below ground.

Step Five: Clean up the Extra Debris

Once you’ve removed the blockage and water is flowing through your outdoor drain again, it’s worth spending a bit of extra time making sure that the problem doesn’t come back. Using a hose, preferably a pressure hose, clear away any excess debris that has built up around the drain.

Don’t blast a garden hose down the line until the standing water has actually dropped. Otherwise you will just flood the patio with foul waste.

Lateral drains carry wastewater from homes to the sewer in the street. The pressure from your hosepipe should dislodge the remaining elements of the blockage that you’ve loosened with your hands or drainage rod. The cleaner you can get your drains, the longer it will be until you need to do this again.

Step Six: How to Unblock a Blocked Outside Drain That Won’t Clear? Call in the Professionals

Outside drainage issues, including outdoor drain blockages, tend to be more complex problems than your usual sink blockage. While they are manageable through DIY techniques, these methods aren’t always effective. If they don’t work, we recommend you avoid attempting more extreme techniques. Damage to your external drainage may occur and you can make the problem worse.

When you can’t get past that stubborn blockage, call drainage experts such as our team at Homecure Plumbers. We have the expertise and tools to extract even the toughest drain blockage. A professional hand is often all it takes to get your plumbing back to normal.

Outside drain unblocking with a jetter from £165 + VAT. Subject to diagnosis; prices vary depending on the job and access. Prices apply during office hours; parking or the congestion charge may be added. See our blocked drain service or call 0203 504 4000.