Home Improvement

Common Causes of Sewer Line Blockages and How to Fix Them

Blockages in sewer lines are a homeowner’s worst nightmare. They can cause foul odors, clogged drains, and even sewage backups into your home. Understanding the common causes of sewer line blockages and how to repair them is critical for keeping a plumbing system in good working order. In this comprehensive guide, we’ll look at the most common causes of sewer line blockages and how to fix them.

  1. The Roots of a Tree

Tree roots are the most common cause of sewer line blockages. Roots require both moisture and nutrients, and sewer lines provide both. Tree roots can infiltrate and grow inside sewer pipes over time, causing obstructions and damage.

How to Repair It

  1. Rooter Service: Professional plumbers can use a rooter machine to remove tree roots from sewer lines. A rotating blade on this machine cuts through the roots, restoring proper flow.
  2. Chemical Treatments: Some chemical treatments are intended to kill tree roots and prevent them from regrowing. Typically, these treatments are poured into the sewer line.
  3. Sewer Line Replacement: In severe cases where the sewer line has been extensively damaged, replacing the affected section of the pipe may be necessary.
  4. Regular Maintenance: Regular maintenance, such as regular inspections and the installation of root barriers, can help prevent tree roots from invading your sewer lines.
  5. Grease and Fat Deposition

It is common to pour grease and fat down the drain. These substances can accumulate inside sewer pipes over time, causing blockages. Grease and fat cool and solidify, trapping other debris and causing stubborn clogs.

How to Repair It

  1. Hot Water and Detergent: Pouring a solution of hot water and dishwashing detergent down the drain can help dissolve grease and fat buildup. After that, flush with hot water thoroughly.
  2. Plunger or Plumbing Snake: In less severe cases, you can dislodge grease and fat clogs with a plunger or a plumbing snake.
  3. Chemical Drain Cleaners: Chemical drain cleaners designed specifically for grease buildup can be used, but they must be used with caution and in accordance with the manufacturer’s instructions.
  4. Regular Maintenance: Avoid pouring fats and oils down the drain to prevent future grease buildup. Instead, place them in the trash in a sealed container.
  5. Strange Objects

Flushed or washed-down drain foreign objects can easily become lodged in sewer lines. Sanitary products, paper towels, toys, and even jewelry are common culprits.

How to Repair It

  1. Plumbing Snake or Plunger: Using a plunger or plumbing snake, try to remove the obstruction. Avoid pushing the object deeper into the sewer line by being gentle.
  2. Professional Assistance: If the foreign object cannot be removed with simple tools, professional plumber Vancouver WA can retrieve or dislodge it using specialized equipment.
  3. Prevention: To prevent future blockages, educate household members on what should and should not be flushed or washed down drains.
  4. Scale and Mineral Deposits

Hard water causes mineral deposits and scale buildup. Minerals such as calcium and magnesium can accumulate inside sewer pipes over time, reducing pipe diameter and restricting water flow.

How to Repair It

  1. Descaling Solution: Mineral deposits can be dissolved using descaling solutions. Typically, these solutions are poured into the sewer line and allowed to sit for a specified amount of time before flushing.
  2. Professional Hydro-Jetting: Plumbers can effectively remove scale buildup and mineral deposits by using high-pressure water jetting equipment.
  3. Water Softener: Installing a water softener can help prevent mineral buildup in your plumbing system, including sewer lines.
  4. Structural Deterioration

Sewer lines can sustain structural damage over time, particularly in older homes or areas prone to shifting soil or freezing temperatures. Blockages and sewage leaks can occur as a result of cracks, fractures, and collapsed pipes.

How to Repair It

  1. Video Inspection: A sewer camera inspection can determine the extent and location of structural damage. This data informs repair or replacement decisions.
  2. Trenchless Repair: Trenchless repair methods such as pipe lining or pipe bursting can be used to rehabilitate sewer lines without extensive digging in some cases.
  3. Traditional Excavation: In extreme cases, traditional excavation may be required to repair or replace damaged sewer lines.
  4. Preventive Maintenance: Regular inspections can detect early signs of structural problems, allowing for proactive repair or replacement.
  5. Shifting Ground or Settling Soil

Sewer lines can shift or settle as a result of changes in the soil or ground, resulting in misaligned or sagging pipes. This can result in blockages and reduced flow.

How to Repair It

  1. Regrading and Compaction: Correcting the soil or ground slope around the sewer lines may help prevent further shifting or settling.
  2. Pipe Realignment: Using specialized equipment, professional plumbers can realign misaligned pipes.
  3. Pipe Replacement: To restore proper flow, the sewer line may need to be replaced if it has sagged or is severely misaligned.
  4. Corrosion and Degradation

Sewer pipes can corrode and deteriorate over time, especially if they are made of older materials such as cast iron or clay. Corrosion and deterioration can cause weak spots, cracks, and pipe collapses.

How to Repair It

  1. Pipe Inspection: Routine inspections can detect corrosion or deterioration. Early detection enables timely repairs.
  2. Pipe Lining: By applying a lining material that seals and reinforces the interior of the pipe, trenchless pipe lining methods can be used to rehabilitate corroded pipes.
  3. Pipe Replacement: Pipe replacement may be required in cases of severe corrosion or deterioration.
  4. Subzero Temperatures

In colder climates, freezing temperatures can cause water inside sewer pipes to freeze, resulting in blockages. Frozen pipes can burst and cause extensive damage.

How to Repair It 

  1. Thawing: If you suspect frozen pipes, thaw them with a gentle heat source such as a hairdryer or space heater. Use of open flames or excessive heat can damage the pipes.
  2. Insulation: To avoid future freezing, insulate exposed sewer lines and seal any gaps or cracks in the foundation of your home that allow cold air to enter.
  3. Winterization: If you live in an area with extremely cold temperatures, consider having your sewer lines professionally winterized in preparation for winter.
  4. Sewer Lines That Have Been Bellied or Sunken

When a section of the pipe sags or settles, it creates a low point where waste and debris can accumulate.

How to Repair It

  1. Professional Evaluation: A professional plumber can assess the extent of the sagging or sunken area and recommend the best repair method, learn more about True Plumbing.
  2. Trenchless Repair: In many cases, trenchless methods such as pipe relining can be used to repair bellied or sunken sewer lines without the need for excavation.
  3. Traditional Repair: In more severe cases, traditional excavation may be required to access and repair the damaged section.
  4. Soap Scum and Grease

Over time, grease and soap scum can build up inside sewer pipes, causing stubborn blockages. Soap scum can combine with mineral deposits to form a tough, tenacious clog.

How to Repair It

  1. Chemical Drain Cleaners: You can use commercial drain cleaners that are specially formulated for grease and soap scum. Take safety precautions and follow the manufacturer’s instructions.
  2. Hot Water and Vinegar: A solution of hot water and vinegar can aid in the removal of soap scum and grease. After that, flush with hot water thoroughly.
  3. Plunger or Plumbing Snake: To dislodge clogs caused by grease and soap scum, use a plunger or plumbing snake.
  4. Preventive Measures: Preventive measures include properly disposing of grease and fats, avoiding excessive soap use, and using screens or strainers in drains to catch debris.
  5. Disposable Wipes And Non-Disposable Items

Despite their name, flushable wipes can cause sewer line blockages. Many of these wipes do not degrade as easily as toilet paper and can clog pipes. Non-flushable items such as dental floss, cotton swabs, and hygiene products can also cause clogs.

How to Repair It

  1. Cease Flushing Non-Flushable Items: Avoid flushing non-flushable items such as flushable wipes, dental floss, and sanitary products down the toilet.
  2. Plunger or Plumbing Snake: Use a plunger or plumbing snake to clear any blockages caused by these items.
  3. Professional Assistance: If the blockage persists, professional plumbers can use specialized equipment to clear the sewer line.
  4. A Lack Of Routine Maintenance

Failure to maintain your sewer lines on a regular basis can result in blockages and other plumbing problems. Preventative measures can identify and address potential issues before they become major issues.

How to Repair It

  1. Scheduled Inspections: Have a professional plumber perform regular inspections to detect and address issues before they become blockages.
  2. Hydro-jetting: By cleaning the inside of the sewer lines and removing buildup, hydro-jetting can help prevent clogs.
  3. Education: Educate household members about proper disposal practices and the importance of avoiding common blockage causes.


Sewer line blockages can cause inconvenience and potentially costly repairs. Understanding the common causes of blockages and taking proactive measures can help you reduce the likelihood of experiencing plumbing problems. Regular maintenance, responsible disposal, and professional assistance as needed are critical to keeping your sewer lines clear and your plumbing system running smoothly. If you do encounter a stubborn blockage, contact a licensed plumber for expert diagnosis and repair.

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