6 Common Causes of Sewer Backups and How to Fix Them

Sewer backups can be a homeowner’s worst nightmare, causing damage to property and posing significant health risks. But what if you could prevent this messy situation from happening in the first place? This blog post will explore the common causes of sewer backups, how to identify potential issues, and the best prevention and maintenance tips to keep your sewer system running smoothly. By understanding the root causes of these problems, you’ll be better equipped to tackle them head-on and avoid the costly consequences of a backed-up sewer. Mainline Water & Sewer in Edmonton has professionals available to discuss your issues with a person.

Short Summary

  • Common causes of sewer backups include clogged pipes, tree root intrusion, damaged sewer pipes and heavy rainfall.
  • Regular inspections, maintenance and disposal of materials can help prevent sewers from backing up.
  • Professional services such as hydrojetting and video inspection are recommended for optimal performance in plumbing systems.
A diagram showing the causes of sewer line damage, including tree roots, corrosion, clogged pipes, and extreme temperatures

Main Factors Leading to Sewer Backups

Four primary factors can lead to sewer backups: clogged pipes, tree root intrusion, damaged sewer pipes, and heavy rainfall. Each of these factors contributes to disrupting your sewer system’s functionality in different ways.

By recognizing the causes of sewer backups, you’ll be better equipped to implement preventive measures and maintain the overall health of your sewer system.

Clogged Pipes

Clogged pipes are a common cause of sewer backups and can be triggered by grease, hair, or other solid materials accumulation in drain pipes. Additionally, a failed sump pump can also lead to clogged pipes. When pipes become obstructed, water cannot flow freely, leading to backups and potential damage to your plumbing system.

Regular maintenance and proper disposal of materials can significantly reduce the risk of clogged pipes and the havoc they can wreak on your home.

Tree Roots Intrusion

Tree roots significantly contribute to sewer backups, especially in older homes with clay or cast iron pipes. Even if you don’t have trees on your property, nearby tree roots can still invade your sewer pipes, causing blockages and eventual backups. Telltale signs of tree root intrusion include slow-flowing drains and gurgling noises from your toilets.

To prevent tree root intrusion, it’s essential to address the issue early, removing any roots before they can spread to your pipes.

Damaged Sewer Pipes

Old, damaged pipes can also lead to sewer backups. Pipes made of cast iron and clay are particularly prone to cracking, which can result in sewer backups. Signs of damaged sewer pipes include sewage backups and blockages, sewer gas odour, mould issues, slow drains, and raw sewage smell in the residence.

When faced with damaged sewer pipes, it’s essential to consult a professional plumber who can assess the damage and carry out the necessary repairs or replacements.

Heavy Rainfall and Municipal Sewer System Overload

Heavy rainfall can overload the municipal sewer system, leading to backups and overflows in residential plumbing. Excessive precipitation can also result in flooding, leading to sewage backups in residential pipes.

In such cases, a properly functioning sump pump is crucial to helping prevent basement flooding and property damage.

Identifying Sewer Backup Symptoms

Recognizing the early signs of a sewer backup is crucial in preventing extensive damage and costly repairs. Typical indications of a sewer backup include unpleasant smells, sinks and toilets draining slowly, and gurgling sounds emanating from drains.

If you notice any of these symptoms, contact a professional plumber immediately.

Multiple Drains Clogging

If you notice multiple drains clogging simultaneously, this could indicate a more significant issue with your sewer line, such as a clog in the main drain, a broken pipe, or a problem with the municipal drain cleaning service or sewer system.

In such cases, it’s essential to call a professional plumber to inspect the clogged sewer line and determine the underlying cause of the clog so they can advise on the best approach to remedy the issue.

Bubbling Near Drains

Bubbling near drains is caused by air bubbles that form when a sewer drain pipe becomes clogged. An unpleasant odour and gurgling noises usually accompany this.

Large bubbles near the drain may indicate sewer backup caused by trapped air in clogged drains. If you notice this symptom, addressing the issue promptly is essential to prevent further damage.

Toilet Issues

Toilet issues, such as slow flushing or water rising higher than usual in the bowl, can also indicate a sewer backup. If plunging the toilet doesn’t resolve the issue, it could indicate a more significant problem with your home’s sewer system. In such cases, contacting a professional plumber is crucial to address the issue and prevent further damage.

Prevention and Maintenance Tips

Preventing sewer backups is crucial for maintaining the health of your sewer system, protecting your property, and avoiding costly repairs.

Some key prevention and maintenance tips include inspecting your sewer lines regularly, avoiding pouring grease down drains, flushing only toilet paper, cleaning your sewer line regularly, and replacing old sewer lines.

Avoid Pouring Grease Down Drains

One of the most essential tips for preventing sewer backups is to avoid pouring grease down drains. Grease can solidify and create blockages in your pipes and floor drains, leading to bottlenecks and potential damage to your plumbing system.

Instead, transfer the grease into a container and dispose of it in the trash or compost bin, or use it to create soap.

Flush Only Toilet Paper

Flushing only toilet paper is essential for maintaining the health of your sewer system and preventing backups. Non-flushable items like wipes, paper towels, and feminine hygiene products can cause clogs and backups, resulting in expensive repairs and potential health risks.

Always dispose of these items in the trash instead of flushing them down the toilet to maintain a healthy sewer system.

Regular Sewer Line Cleaning

Regular sewer line cleaning is essential to ensure optimal performance and prevent backups. It is suggested that your sewer lines be cleaned every 18-22 months. Regular maintenance will help keep your pipes clear of debris and reduce the likelihood of clogs and backups, ultimately saving you money and potential headaches.

Types of Sewer Pipes and Their Impact on Backups

The type of sewer pipe employed in your home can impact backups, but the primary causes of backups are usually clogs, tree roots, cracked pipes, and rain.

The four most common sewer pipe types are cast iron, clay, Orangeburg, and PVC and ABS. Understanding the characteristics of each type of pipe can help you better assess its impact on your sewer system and the likelihood of backups.

Cast Iron Pipes

Cast iron pipes were commonly used in sewer systems before the 1970s and are typically found in older homes. These pipes are prone to corrosion and sewer backups, as they may begin to fracture underground at the end of their useful life.

If your home has cast iron pipes, it’s essential to monitor their condition and consider replacing them to prevent sewer backups.

Clay Pipes

Clay pipes are another widely used type of sewer pipe, but plastic sewer pipes have since replaced them. These pipes are highly susceptible to tree root infiltration and sewage backups because they cannot provide a reliable seal against water.

If your home has clay pipes, monitoring their condition and addressing any potential issues to prevent backups is essential.

Orangeburg Pipes

Orangeburg pipes are made of bituminized fibre and were used as sewer pipes. Due to their brittleness, they are particularly susceptible to sewer backups.

If your home has Orangeburg piping, it is recommended that you replace the pipes with a more durable material as soon as possible to avoid potential backups and damage.

PVC & ABS Pipes

PVC and ABS pipes are flexible, affordable, and durable options for sewer systems. Although they are not as resilient as other types, such as cast iron or copper, they are still popular for modern plumbing and drainage systems due to their ease of installation and affordability.

PVC and ABS pipes offer reliable solutions for preventing sewer backups and maintaining the health of your sewer system.

Professional Drain Cleaning Services

Professional drain and sewer cleaning services, such as hydro jetting and sewer camera video inspection, can be crucial in maintaining your sewer system and preventing backups.

These services can identify and address issues with your sewer system before they become more significant problems, ultimately saving you time, money, and stress.


Hydrojetting is a powerful and recommended method for cleaning pipes. This technique uses high-pressure water to remove clogs and debris that have built up in the pipes throughout the plumbing and sewage system. Hydrojetting removes grease and sludge from kitchen sink drains and tree roots from sewer lines.

By employing hydrojetting as a preventive measure, you can keep your pipes clean and avoid potential plumbing and drainage issues.

Sewer Camera Video Inspection

Sewer camera video inspection is also a vital tool for larger underground pipes. This technology utilizes a small camera connected to a cable to inspect underground water and sewer pipelines for potential damages, clogs, blockages, cracks, or leaks.

By thoroughly inspecting your sewer system, professional plumbers can identify and address any issues before they become more significant problems, helping you maintain a healthy sewer system and avoid costly repairs.


In conclusion, understanding the causes of sewer backups and identifying early warning signs are crucial to preventing costly damage and health hazards. By implementing preventive maintenance measures and utilizing professional drain cleaning services, you can maintain the health of your sewer system and protect your property.

Remember, a well-maintained sewer system not only saves you money in the long run but also preserves the environment and ensures the well-being of your family. Take charge of your home’s plumbing health today and safeguard your property from the devastating effects of sewer backups.

Frequently Asked Questions

What causes sewage backups?

Blockages in sewer lines often cause sewage backups due to the build-up of debris, grease and other materials or damage to the main sewer line.

Rainwater entering the system and tree roots can also cause backups in some cases.

What causes the sewer to back up in the basement?

Sewer backups typically occur when there are clogs or build-ups in the sewer pipes caused by grease, solid materials, and sometimes even damaged sewer lines.

Furthermore, if your basement’s sump pump fails, this can also cause a sewer backup on your basement floor.

What can I do to stop sewer backup?

To stop sewer backup, one should take preventive measures such as not pouring fats or oils down drains, disconnecting downspouts, foundation drains and weeping tiles from the drain service the municipal drain, installing a backwater valve, having a sump pump installed, and regularly checking for clogged sewer drains.

These steps can help prevent sewer backups and the costly damage they can cause. It is important to be proactive and take the necessary steps to protect your home and property from sewage backups.

How do I clean my sewer line at home?

If you want to clean your sewer line at home, the best combination is baking soda, vinegar, and water pressure. Mix two parts vinegar to one part baking soda in 60 gallons of water, then pour the mixture down your drain while using a plunger or snake to help break up any debris blocking the flow of the floor drain.

This should help unclog the blockage in your sewer line.

Contact Mainline Water & Sewer for a free professional consultation.