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Prevent sewer backups

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A sewer backup occurs when a waste line is blocked, causing wastewater to backup into the home. In the United States:

  • Over 500,000 sewer backups happen every year, according to the Association of California Water Agencies.
  • Sewer backups are increasing at an average rate of 3% per year, according to the Civil Engineering Research Foundation.
  • Between 23,000 and 75,000 sanitary sewer overflows occur each year, according to EPA estimates.
  • The estimated out-of-pocket costs for sewer backup damage in the home are between $2,000 and $10,000. Actual costs can be much higher when factoring in personal property and dwelling damage. (

To prevent sewer backups in the home, properly dispose of household waste, install a backup water valve, inspect and trim tree roots growing near the sewer line, and add more water to ensure waste moves into your septic tank or city sewer line.

What is a sewer backup?

A sewage or sewer backup happens when subsurface water comes up through the sewer or drainage system into your home, such as your toilet, sinks or shower. A sewer backup may be caused by pipe deterioration, tree roots intruding into the line or by improperly disposing of sanitary products, toilet paper, rags, fat, grease or oil.

Improperly diverting downspouts, stormwater or groundwater into the sewer system can also cause sewer backup into the home due to an overabundance of water overwhelming the drainage system. The private line on the property is often the cause, but sometimes, the sanitary sewer system can overflow and backfill into the public line and private homes.

When is the City Responsible for Sewer Lines?

The city’s responsibility usually begins at the main sewer line that sits beyond your private property boundaries. You are typically responsible for the sewer line on your property, including the upper and lower lateral lines. Though this line typically extends beyond your property, you are usually still responsible for it until it connects to the main sewer line.

How to prevent a sewer backup

There are several things homeowners, renters and property owners can do prevent a sewer backup:

  • Flush only toilet paper.
  • Keep sewer lines clear of tree roots.
  • Do not plant trees or bushes near sewer lines or laterals.
  • Hire a professional to install an exterior cleanout.
  • Avoid putting fat, grease and oil down the drain.
  • Line or replace old pipes.
  • Install a sewer backup valve.
  • Avoid connecting downspouts, french drains, sump pumps or flood control systems to the sanitary sewer line.
  • Hire a professional to inspect your plumbing and sewer lines.
  • Elevate the house drain

Main causes of sewer backups

The main causes of sewer backups in the home are usually homeowner or tenant errors. Most often, a backup in the sewer line happens from:

  • Flushing sanitary products, flushable wipes, diapers and paper towels down the toilet.
  • Clogging pipes with fat, oil, grease, coffee grounds, eggshells and fibrous vegetables.
  • Planting bushes and trees close to sewer lines can cause roots to infiltrate the lines.
  • Excess rainwater being diverted into sewer systems.
  • Pipes aging and deteriorating, causing a break or fracture in the sewer line.

The EPA estimates most United States sewer system lines are an average of 33 years old. Aging infrastructure can also be a cause of sewer backups into the home from the main sewer line.

The dangers of sewer backup

Sewer backups can cause damage to your home and belongings, depending on the extent of the backup. Not only is the cleanup intense and smelly, but it can also be costly to replace expensive bathroom and kitchen cabinets and fixtures.

If the water is not cleaned up quickly and thoroughly, mold could develop in your home. Wastewater can also contain bacteria, parasites, viruses and other toxins that can make you and your family very sick.

How expensive is a sewer backup?

A sewer backup without dwelling or belonging damage is still fairly expensive to repair. Estimates range from $2,000 to $10,000 for the cleanup and restoration, and it can get costly quickly if there is more damage, such as:

  • If the cause is unknown, a plumber will need to do a camera inspection with an average cost of $560.
  • If a tree root was found to be the cause, it could cost about $600 to remove.
  • If a sewer line needs to be replaced, it can cost between $50 to $200 per foot.
  • Excavation of the sewer line to replace it costs between $6 to $15 per linear foot.
  • If your finished basement needs carpet, baseboards and walls ripped out and replaced, it will cost an average of $6,000 or more.

If all of these things happen, the cost of the sewer backup would be at least $10,000 in addition to cleanup and restoration costs. Other damage can also occur.

What does sewer backup insurance cover?

Sewer backup coverage under a home insurance policy pays for accidental direct physical loss to your dwelling or personal property. Exact coverage limits vary by carrier, and almost all providers require an optional endorsement on your homeowners policy for this specific coverage. Consider your coverage limits when purchasing sewer backup insurance, which caps how much the insurance company will pay in the event of a backup. Given the hefty price tag that comes with sewer backups, sewer backup insurance is probably worth looking into, particularly if you live in an older home or area where the sewer lines are likely older, too.

What to do if you experience a sewer backup

A sewer backup can cause damage to your home and belongings and lead to mold and disease if not cleaned up promptly. To prevent further damage and limit disease exposure there are some things you can have a professional do (or some you may be able to do yourself):

  • Shut off power to the affected areas of your home.
  • Use a wet vac to remove liquids and solids.
  • Disinfect solid floors and walls.
  • Remove and discard absorbent materials like carpets and wallboard.
  • Flush and disinfect pipes and plumbing fixtures.
  • Clean ductwork if needed.

Sewer backups are most often caused by clogged pipes from household materials, tree roots or pipe failures. Avoid flushing anything but toilet paper down the toilet and putting fats, oils, grease and other clogging materials down the drains. If a sewer backup occurs, take pictures of the damage to document it and begin cleanup immediately to prevent illness and further damage.

Written by
Mandy Sleight
Insurance Contributor
Mandy Sleight has been a licensed insurance agent since 2005. She has three years of experience writing for insurance websites such as Bankrate, MoneyGeek and The Simple Dollar. Mandy writes about auto, homeowners, renters, life insurance, disability and supplemental insurance products.