underground pipe

How to unclog an underground outdoor drainage pipe?

If your underground drainage pipe is blocked, it can be a little more complicated to unclog than an indoor drain. While many indoor drains can become easily unclogged with some hot water and vinegar, an outdoor drain is slightly more difficult to manoeuvre. 

Clogged underground drains can cause serious damage to your property if not fixed in a timely manner, so it’s a good idea to be proactive if you think your drain pipe is blocked. 


In this guide, we’re going to show you several ways you can try to unclog an underground drainage pipe, and how you can prevent further blockages from occuring in the future. Let’s take a look!

What is an underground drain?

An underground drain is a drain that is connected to your gutter downspout. Its principal function is to direct any water and sewage away from your property, either directly to a sewage pipe to the street outside your home.

How can I know if my underground drainage pipe is blocked?

Underground drains can become clogged easily, as they frequently carry leaves, debris, dirt, and even litter through their systems. Here are some easy ways to tell whether or not your underground drain is blocked:


Observe your gutter downspout and look out for any leaks or water spillage at the seams. If you notice water spraying or even mild leaking, this is a reliable indicator that there’s a blockage in the underground drainage pipe, which is pushing water back up through the system.


If your gutter spout looks as if it’s blocked with leaves, litter, or any other form of debris, you might be dealing with a drain blockage. If you can see it and reach it, you can try removing some of the debris to see if the blockage is uniquely at the surface level or deeper within the drainage system.

Test with a garden hose

If you have a garden hose on hand, you can easily check the efficiency of your underground drainage system, and quickly identify if there’s a blockage. Place your garden hose nozzle into the downspout and turn on your hose at full power. If your drainage system isn’t blocked, the water should flow naturally through the system and won’t come back up. If your drain is blocked, the water from the hose will start to spill out or spray up.

Look for signs of early flooding

If your underground drainage system isn’t working correctly, you’re likely to see water pooling in unusual places in your garden, particularly on grass. Large ‘swampy’ pools of water are a reliable indicator that there’s a drainage problem in your underground system, and you should take steps to unclog it before it does excessive damage.

The rain test

All underground drains will have an exit point, and you can observe the exit point if you suspect that there’s a blockage in one of your drainage pipes. To perform this test, wait until after heavy rainfall, and observe the exit point carefully. If no water is draining, there’s most likely a blocked pipe underground.

What happens if my drainage system becomes clogged?

If your underground drainage system becomes blocked, it can cause a large number of expensive problems both in the area surrounding your home and your home itself, especially if your home tilts upward (making it vulnerable to flooding). Blocked drainage systems can cause the following problems:

Damp and rot

Even if your underground drain pipes don’t burst, the accumulation of water in the underground system can still end up causing expensive damage. This can include rotting wood, damp, and mould, all of which creates a health and safety risk for those living in your property, and can cost thousands to fix.

Flood damage

If your pipe bursts under the pressure of the blocked water, you could end up seeing thousands of pounds worth of damage done to your home, especially in the underground foundations. In the worst case scenario, water damage can impact the structural integrity of your home, making it hazardous and unsafe – not to mention that it could also cause your home to plummet in value.

How to unclog an underground outdoor drainage pipe

So, what can you do to fix a clogged underground drainage pipe? Here are four methods you can employ at home to prevent further damage and unclog your drain pipe:


Snaking can be an effective way to unclog a drain pipe that is clogged up with leaves and other debris. A drain snake is simply a slender piece of metal that you can push through the drainpipe to release anything that might be blocking the water flow. Depending on the length of your drain, you may have to hire professional drain clearing services to snake the drain safely.

Jet hose

Another method you can use is a jet hose: if you have a powerful garden jet hose, you can try to use the high water pressure of the hose to dislodge any debris. This may or may not be successful depending on the strength and pressure of your hose; a traditional garden hose probably won’t be powerful enough to dislodge stubborn debris.

DIY methods

Some homeowners swear by classic home remedies when it comes to blocked drains. For example, you can try to unclog any debris using home DIY methods, such as white vinegar, baking soda (bicarbonate of soda in the UK), or chemical cleaners. While this may work for mild blockages, you might find that the problem simply reoccurs as the drains have not been fully emptied of debris.

How to prevent underground drains from getting blocked

As with all home protection, the key to preventing a blocked drain is in the prevention. Most drain blockages are caused by falling debris, and there are many affordable ways you can prevent debris from entering into your drain pipe. 

One easy way is to protect your gutters. You can do so by placing a filter over your gutters  and downspout: this will allow water to drain through, but blocks leaves and any other encumbering debris from getting into the drain pipe.

When to call the experts?

If you’re unable to successfully unclog the drain, or you don’t have access to the necessary tools to do so, it’s a good idea to call in drainage experts. Most drain repair services UK will send teams fully equipped with protective PPE gear, as well as professional unclogging tools that will be able to get the job done safely and efficiently.

Why use professional drain services?

As previously mentioned, letting a blocked drain accumulate water under your home can end up causing significant damage to the integrity of your property. Once you’ve been able to identify a blockage, it might not be clear for just how long water has been blocked, and hiring a professional team to look at it right away might be able to save you from the hassle – and cost – of preventable water damage. 

Plus, using snaking devices and jet hoses can be dangerous if you’re not adequately familiar with these tools; you could end up causing damage to the drain, or unintentionally triggering a burst pipe. For an efficient, timely, and safe unclogging of your drains, call in a drain repair service.