6 Signs That Your Sewer System Needs Repair

By Krystal Nanan
Published: March 6, 2019 | Last updated: July 5, 2023
Key Takeaways

Knowing the early warning signs of sewer problems can help mitigate property damage and minimize the ensuing repair and restoration costs.

Sewer systems are one of the most critical utilities in any residential or commercial building. At the heart of these systems is a network of piping, called sewer lines, which are responsible for channeling all wastewater originating from sinks, toilets, baths, etc. to the municipal sewer mainline.


Considering the type of fluids that these pipelines transport on a daily basis, it is usually not a pleasant experience when they do not function as intended. Sewer problems are one of those issues homeowners hope they never to deal with.

However, like any other pipe, sewer lines are susceptible to wear and damage, which can lead to unpleasant and inconvenient situations in addition to costly repairs and sewer rehabilitation work. (Read The Essential Pros and Cons of Trenchless Sewer Rehabilitation.)


Common Causes of Sewer System Damage

Over its lifetime, sewer pipes may be exposed to several hazards which can compromise its integrity. Loss of structural capacity can eventually lead to cracks, rupture, and even collapse of the pipeline. If left untreated, sewer pipeline failures can cause damage to property, encourage mold growth, and attract pests to name a few.

Some of the most common causes of sewer system damage include:


Like drains, sewer lines can also become clogged. Clogging interferes with the flow of the wastewater through the pipeline, creating sewage backups in the system. Backups can apply added pressure on the walls of the pipe, which can eventually lead to overstress and rupture. While clogging in one toilet, sink, or tub may not be indicative of sewer problems, if every flush causes a backup, it may be worthwhile to contact a licensed professional to perform an investigation.


Corrosion is a chemical or electrochemical reaction which causes the walls of steel pipes to dissolve or deteriorate. During the corrosion process, the pipe’s wall thickness gradually reduces, resulting in a significant decrease in the pipe’s load carrying capacity. If left untreated, corrosion can lead to cracks, leaks, or pipe rupture.

Free Download: How To Detect Pipe Corrosion in Underground Force Mains Plus Must-Have Corrosion Detection Equipment

One of the most common types of corrosion found in sewer systems occurs due to the action of bacteria, where the metabolic activity of microorganisms results in the release of corrosive H2S and CO2 gases.

Tree root infiltration

Tree roots naturally grow toward sources of moisture. The pressure applied by growing roots is usually enough to penetrate exterior pipe walls. Roots can also enter sewer lines via loose joints, where they grow until they eventually break through the piping.

Aging pipes

While plastic sewer pipes have become the norm, many older homes consists of cast iron or clay piping which can deteriorate and lose structural integrity over time. Some joints and sealants may also become a site for leaks due to wear and tear from continuous usage.

6 Signs That Your Sewer System Needs Rehabilitation

While the early onset of some problems is impossible to detect with professional assistance, there are other readily visible warning signs which homeowners can look out for to minimize the undesirable effects of sewer-related issues.

Some of the most common symptoms of sewer damage include:

Foul odors

One of the first, and most obvious signs of sewer system problems is foul odors in and around the household. Pungent smells (similar to the scent of rotten eggs) are an indication that the sewer line’s air-tightness has been compromised or wastewater leaking has occurred.

Pools of septic waste

Another readily visible sign of sewer problems is the pooling of wastewater near the location of the compromised pipe. This pooling generally do not dissipate until the issue is resolved and are also accompanied by unpleasant foul odors.

Backup and blockages

Backups and blockages are characterized by improper drainage and rising water in toilets, sinks, tubs, etc. While backups can occur in plumbing fixtures occasionally, frequent backups (for example, if sewage backs up every time the toilet is flushed) can be indicative of issues with the sewer line. Similarly, while blockages are not necessarily a cause for alarm, simultaneous obstruction in more than drain may be worthy of investigation.

Backups and blockages related to sewer systems typically start at the lowest level of the home and tend to be visible in all fixtures.

Lush patches of vegetation

While lush lawn grass may seem like a good thing, random spots of healthy-looking vegetation can indicate sewer issues. Leaks in sewer piping can result in wet soil in the vicinity of the affected location. As nutrient-heavy wastewater rises to the surface, it fertilizes nearby grass, leading to rapid growth and unusual lush green colors.

Lawn indentations

In addition to lush lawns, indentations in the soil can be the result of sewer leaks. Damaged piping can saturate the surrounding soil, causing it to settle or dip. A simple method of detecting indentations is to walk around the area where the sewer pipeline is buried to notice if there is any shift in the soil surface. If the leaks are present under paved surfaces, such as a driveway, the soil settlement lead to the formation of cracks. In extreme cases, foundation cracks, settled foundations, or even sinkholes may be observed.

Sudden pest infestation

Another unfortunate side effect of sewer leaks is an unwanted and unexpected increase in pests in and around the home. Rats and cockroaches are especially attracted to the odor of leaking sewers. Not only are these pests destructive, but they can also carry many harmful diseases.

What We've Learned

Sewer leaks, if left unattended to, can result in extensive and costly damage to buildings and landscapes. Early identification of sewer issues is, therefore, crucial to minimizing the ensuing repair and restoration costs. Although there are several types of sewer repair techniques, trenchless rehabilitation is quickly becoming the preferred technique for many homeowners.

Trenchless investigations, such as camera inspections, can help identify the exact location of the pipeline defect, while trenchless repair methods can help restore the integrity of the piping with minimal destruction to the surrounding landscape.

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Written by Krystal Nanan | Civil Engineer

Krystal Nanan

Krystal is a civil engineer and project manager with an MSc in Construction Engineering and Management. Her experience includes the project management of major infrastructure projects, construction supervision, and the design of various infrastructure elements including roadway, pavement, traffic safety elements and drainage.

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