How Do You Know If Your Sewer Line Is Backed Up

WRITTEN BY: Mark Romero


A sewer backup can create havoc in a home, causing thousands of dollars in damage to flooring, furniture, walls, and electrical systems and potentially creating a serious health risk. And unless you have specific sewer backup insurance added to your homeowner policy, that damage is uninsured. 

For most Americans, the risk of a city sewer backup increases each day. 

The American Society of Civil Engineers indicates that the nation’s 500,000-plus miles of sewer lines are, on average, over thirty years old. Every new residence or business that’s built adds to the load on this dated infrastructure.

It’s not surprising that the Civil Engineering Research Foundation is reporting the number of backed up sewer lines is increasing at an alarming rate of about 3 percent annually. 

Even though the city owns and operates the sewer, cities will rarely be held responsible for damage caused by a backup.

City sewers are open systems receiving sewage from every home and business connected to it. Unless negligence can be proven, a city will be held harmless for losses caused by backups.

Locate the Origin of Your Backup

It’s important to remember that a sewer line backup can be caused by the city’s mainline or your linear line. This primary line runs from your house to the city’s line.

It’s important to know where the source of the blockage is coming from because you obviously can’t do anything about a blockage in the city line, but you can fix a problem that originates in your linear line.

Regardless of what is causing the backup, you must get professional help quickly. Ask your neighbors if they are experiencing slow drainage or backups or if their toilets occasionally make gurgling sounds.

These are signs of a backup. If your neighbor(s) are also having issues, the backup is most likely in the city sewer line. Call the city, report it, and request they inspect it as soon as possible. 

If your neighbors aren’t having any problems, then the blockage is likely on your property, in your linear line. Call a professional plumber to get the line inspected.

Common Causes of City Sewer Backups

The same events cause backups in the city sewer or on your property. Listed below are the three most common:

Tree Roots

Trees and shrubs seeking water can send their roots to a sewer line and enter through a small crack or a leak at the joint where your line joins the city line. The root may start very small, even hair-like.

As the tree grows, the root will grow and may even follow the line into your home. Removing tree roots using a “snake” with a cutting tool can be difficult. The line must often be dug up and the blocked area removed and replaced.


Sewer lines aren’t designed to handle large quantities of grease. Grease flushed into the sewer can create a blockage that causes a backup. These backups can be caused by improperly disposed grease from a restaurant or a homeowner who sends cooking grease down the kitchen drain with hot water. 

Non-Flushable Bathroom Waste

The most common objects causing backups in residences are those that aren’t easily water-soluble. This includes some commonly believed to be flushable items, such as tampons and baby wipes.

Even moist wipes listed as flushable can cause issues, especially in older lines. Paper towels, baby diapers, sanitary napkins, and cat litter are other examples of waste that should never be flushed.

Foreign Objects

Now and then, something ends up in the line that has no business being flushed in the first place. Items accidentally dropped into toilets cause backups when they get further down the line. 

Steps to Mitigate Sewer Backup Damage

If your city has a combined sewage and stormwater system. That could cause a rapid backup after a severe storm.

However, in the case of a simple clog, you typically have some time to take preventative action to stop the backup from damaging your home.

If you have coverage

If you have added sewer backup coverage to your homeowner policy, call your agent immediately and get his or her advice on how to proceed.

If all your drains are running slow

If all your drains are slow and your toilets gurgle, you may have a backup pending. Your first call should be to your neighbor to see if they are experiencing the same thing. If they are, it’s a city problem, and you need to contact them immediately.

If Sewage is Backing Up Into Your House

If sewage is backing up in your basement or drains, turn off your water at the main valve. This means you can’t flush toilets or run your taps, but you will also not be adding to the volume of water going into the line.

Other Steps You Can Take

If you have access to the sewer cleanout valve, you can remove the cap to relieve the pressure in your primary line and allow water to spread outside rather than in your home.

The sewer cleanout is a small pipe with a rubber cap. It’s usually located outside your property near the house, although sometimes, in older homes, it can be found on the roof.

Call a plumber, especially if the backup is on your property. You need to get a qualified plumber out quickly to inspect your line (and so you can start using your toilets again).

Before Your Next Sewer Backup

If your home is prone to backups, you may want to install a backwater prevention valve. This is a valve placed in your linear line that allows sewage to flow out but not back in, which prevents backups. The cost of this valve will vary depending on how difficult the installation appears.

Any homeowner could experience a sewer backup. Consider adding it if you don’t have your base homeowner policy coverage. Property damage can be severe, but the real cost is if your line has to be excavated and replaced.

How To Get Sewer Backup Coverage

It’s important to be aware of the potential for sewer backups and take steps to protect yourself from the damage and health risks they can cause.

If you live in an area prone to flooding or your home has a history of sewer backups, it’s especially important to have insurance that will help you pay for the damages caused by this type of disaster.

You can get quotes online for specific sewer backup insurance policies; it only takes a few minutes and could save you a lot of money and hassle in the event of a sewer backup.