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Common Causes of Blocked Drains & How to Prevent Them

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Blocked drains are a common issue that many homeowners face. They can be a nuisance, causing unpleasant odors and water backup, and can also lead to more severe problems if not addressed promptly. Understanding the common causes can help you take preventive measures. This blog post aims to educate you on the common causes of blocked drains and how you can prevent them.

Common Causes of Blocked Drains

Hair and Soap Build-Up

One of the most frequent causes of blocked drains in bathrooms is the accumulation of hair and soap scum. Over time, strands of hair can get tangled with soap residues, forming a thick mass that obstructs water flow. This is particularly common in shower drains and bathroom sinks where hair and soap are most often washed away.


Use a drain filter to catch hair.
Clean your drain regularly with a mixture of baking soda and vinegar.

Food Scraps

Kitchen sinks are notorious for blockages caused by food particles and grease. When food scraps are washed down the sink, they can get stuck in the drain, especially if they are not broken down sufficiently. Grease and oils, which are often poured down the sink, can solidify and create a stubborn blockage that’s hard to remove.


Dispose of food scraps in a compost bin.
Never pour grease or oil down the drain.

Foreign Objects

Children’s toys, sanitary products, and even small pieces of clothing can sometimes find their way into drains, causing immediate blockages. These foreign objects are not meant to be flushed down drains and can cause significant problems, requiring professional intervention to remove.


Educate children on what should not go down the drain.
Dispose of sanitary products and wet wipes in a trash bin.

Tree Roots

In outdoor drainage systems, tree roots can be a significant cause of blockages. Roots seek out moisture and can infiltrate even the tiniest cracks in your drainage pipes. Over time, they grow and obstruct the flow of water, often causing severe damage to the pipes.


Regularly inspect the area around your home for tree roots that may be encroaching on your pipes.
Consider root removal services if necessary.

Mineral Build-Up

In areas with hard water, mineral deposits can accumulate inside pipes over time. These deposits can harden and create an obstruction, making it difficult for water to pass through. This is a more gradual process but can lead to severe blockages if not addressed.


Use a water softener.
Regularly clean your pipes to prevent mineral accumulation.

Toilet Paper Build-Up

Excessive use of toilet paper is a common but often overlooked cause of toilet blockages. While toilet paper is designed to be flushable, using too much of it at once can create a bulky mass that the water pressure may not be sufficient to move. This can result in a clog forming in the U-bend or further down the drainage pipe.

In some cases, the issue may be exacerbated by the type of toilet paper used. Some brands produce thicker or multi-layered sheets that do not break down as easily in water, increasing the likelihood of a blockage. Additionally, if your home’s plumbing system is old or has narrow pipes, it may be more susceptible to blockages from toilet paper build-up.


Be mindful of the amount of toilet paper used. Try to use only as much as necessary.
Opt for toilet paper that is labeled as “septic-safe” or “easily dissoluble” to ensure it breaks down quickly in water.
Educate family members, especially children, about the appropriate amount of toilet paper to use.

Aging Pipes

Corroded or damaged pipes are a ticking time bomb when it comes to drainage issues. As pipes age, they can corrode, weaken, and eventually crack or break, leading to blockages and leaks. The material of the pipe can also play a role; for example, iron pipes are more prone to rusting, while PVC pipes may become brittle over time. These deteriorating conditions can cause sediment and debris to accumulate, creating an obstruction in the flow of water.


Schedule regular inspections of your plumbing system to check for signs of corrosion or damage.
Consider pipe relining or replacement for sections that show significant wear and tear.
Use pipe cleaning agents that are specifically designed to remove rust and mineral build-up.
Consult a professional for a comprehensive plumbing assessment, especially if your home is more than 25 years old.

Incorrectly Installed Pipes

Pipes installed at the wrong angle or without proper fittings can lead to drainage issues. The slope of the pipe is crucial for the gravitational flow of water. If the angle is too steep or too shallow, it can result in water pooling or slow drainage, eventually causing blockages. Incorrectly installed pipes can also lead to “pipe sag,” where a section of the pipe dips below the line, collecting debris and waste.


Always hire a certified professional plumber for any plumbing installations or major repairs.
Request a detailed plan or blueprint before any installation work begins to ensure that the pipes will be installed at the correct angles.
If you suspect that your pipes were incorrectly installed, consider a plumbing inspection to identify and rectify any issues.
For new installations, opt for high-quality materials and fittings to ensure a long-lasting and efficient drainage system.


Understanding the common causes of blocked drains and taking preventive measures can save you both money and stress. Early identification and action are key to preventing blocked drains. By following these tips, you can keep your drains running smoothly and avoid serious plumbing issues.

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