How to Clear a Blocked Gully Drain


A clogged gully drain can lead to substantial water damage and create an unpleasant environment. Clearing a clogged gully drain ensures that your plumbing system will work well. This article will provide the professional and DIY steps and tools to effectively clear a clogged gully drain.

What is a Gully Drain?

A gully drain, or gully trap, is a plumbing fixture that collects and directs wastewater and debris from your roof and downspouts into the main sewer line. This home addition helps prevent water damage and ensures proper wastewater flow.

What You Need

You will need various tools and products to clear a blocked gully drain. Let's explore the different options and how to use them effectively.


This tool creates suction and dislodges blockages in your gully drain.

Why It's Important: Using a plunger helps to loosen and remove debris and blockages, ensuring the free flow of water.

How to Use: Place a plunger over the gully drain and ensure a tight seal. Push slowly and steadily until you feel resistance, then hold the plunger in place for a few seconds before lifting. Repeat this process several times until the blockage is cleared.

Drain Snake

A drain snake clears difficult clogs that cannot be loosened with a plunger and is often reserved for deep-seated clogs within drainpipes. It comprises a coiled metal wire with a wider gap at the end, which is manipulated by rotating a handle as it advances through the pipe. This feature helps break up or retrieve the clog, ensuring proper flow in the plumbing system.

Why It's Important: A drain snake is essential for removing stubborn blockages and debris that a plunger cannot dislodge.

How to Use: Feed the drain snake into the gully drain, rotating it as you push. Continue until you feel resistance, indicating the blockage. Break up the blockage by rotating the snake, then remove it and check if it is cleared.

Baking Soda and Vinegar

These substances are considered effective cleaning agents due to their opposing pH levels. The former is a basic substance, sometimes called sodium bicarbonate or NaHCO3.

On the other hand, the latter is a dilute solution, also known as acetic acid (HC2H3O2). The combination’s difference in pH levels allows them to work together effectively to break down and remove various types of grime and stains in the gully drain.

Why It's Important: This solution is gentle on your pipes and can help dissolve grease and other organic matter causing blockages.

How to Use: Pour 1 cup of baking soda down the gully drain, followed by 1 cup of vinegar. Let the mixture sit for two to three hours. After that, use hot water to rinse the mixture from the drainage system.

Chemical Drain Cleaner

This cleaning agent unclogs gully drains blocked by hair, food, or other organic materials. These cleaners typically contain strong acids or alkalis that dissolve at least some of the material, causing the clog. They are available through hardware stores and can be used to clear clogs close to the drain opening, but they may need to be more effective for clogs further down the drain.

Why It's Important: Chemical drain cleaners are effective for removing stubborn blockages, but use them cautiously and follow the manufacturer's instructions.

How to Use: Follow the manufacturer's instructions for application and dosage, pour the solution down the gully drain, let it sit for the recommended time, and then flush the drain with hot water to rinse.

Plumbing Snake

This flexible and slender tool helps dislodge clogs deep within pipes. It consists of a long, coiled metal wire with a handle on one end and a specialised head on the other. 

They are available in various sizes and styles to address different drain types and clog severities, from hand-cranked models for minor clogs to motorised versions for more significant blockages. 

Why It's Important: Plumbing snakes are preferred over chemical drain cleaners as they provide a mechanical approach to clearing clogs, which is more environmentally friendly.

How to Use: The plumbing snake manually inserts the flexible coil into the drain until it reaches the obstruction. The head of the snake then breaks up, hooks, or twists the clog so it can be pulled out or flushed away. This process can be repeated as needed until the blockage is cleared. 

Steps on How to Clear a Blocked Gully Drain

To effectively clear a blocked gully drain, follow these steps:

1. Determine the source and nature of the blockage. Check the gully drain for any visible signs of blockage, such as debris or grease buildup. If a clogged downspout causes the blockage, clear the downspout by removing any debris or leaves.

2. Choose the appropriate tool based on the type and severity of the blockage. For example, if the blockage is caused by grease buildup, a chemical drain cleaner may be the best option. If the blockage is caused by debris, a drain snake or plunger may be more effective.

3. Use the chosen tool to clear the blockage. For example, if using a drain snake, feed the snake into the gully drain and rotate it as you push until you feel resistance. Break up the blockage by rotating the snake, then remove it and check if it is cleared.

4. Use hot water to flush your drain to clear the blockage and remove any residue or debris thoroughly.

5. Repeat if necessary. If the blockage persists after the first attempt, repeat the process until the blockage is cleared.


When dealing with a blocked gully drain, there are several important considerations to keep in mind:

1. Regular cleaning and maintenance can help prevent blockages. Check your gully drain regularly for signs of blockage and promptly clear any debris or buildup.

2. Avoid using harsh chemicals. They can harm the environment, damage your pipes, and cost you more money in the long run. Instead, opt for natural and non-toxic solutions like baking soda and vinegar.

3. If the blockage persists, contact a licensed plumber to help you. They can use specialised equipment and techniques to clear the blockage and properly ensure your plumbing system functions.

4. Use a drain screen. Installing a drain screen can help catch debris and prevent blockages.

5. Regularly check your downspouts for any signs of blockage or damage and clear them promptly.

Frequently Asked Questions About Unblocking Gully Drains

What is the purpose of a gully trap?

The gully trap collects and directs wastewater and debris from your roof and downspouts into the main sewer line.

What are the gully requirements in NSW?

In New South Wales, gully traps must be installed at the base of downspouts to prevent water damage and ensure proper wastewater flow.

Does rainwater need a gully?

Yes, the gully trap directs the rainwater to prevent water damage and ensure proper wastewater flow.

Where does gully water go?

Gully water flows into the main sewer line and goes to the sewage treatment plant.

Should a gully hold water?

No, a gully should not hold water. If it does, it may indicate a blockage or improper installation.

What can I do if nothing else works?

If you need help clearing a blocked gully drain and nothing seems to work, contact All Needs Plumbing for professional assistance. Our team offers a $0 callout fee, $150 off hot water systems, a 15% discount for seniors, and 24/7 same-day services. Don't hesitate to reach out for expert help. Contact us today.

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