What should I do when my basement floods with sewage?

technical drawing of a basement toilet under a glass block window

What should I do when my basement floods with sewage?


Sewage backups are a disaster.  But we don’t have to tell you that.  If you’re experiencing one, there’s only one question on your mind.  What should I do? It’s easy to be overwhelmed by the situation. Your basement or living area may be flooding.  Stay calm, know that it can be fixed, and read on.

Stop the sewage from coming into your home

So there’s human waste flowing up from your tub, toilet, or drain.  How do you even begin to fix this problem? The first step is to control the source of the damage.  You can’t clean up the sewage if it’s still hemorrhaging into your home. But how? What if you aren’t a plumber?  What if you don’t have the right tools?

First, try to assess what is causing this backup.  You don’t necessarily have to be a plumber to make a few deductions about the source of the issue.  When the sewage backup started, were you:

  • Using your dishwasher
  • Using your washing machine
  • Using a shower
  • Draining a tub

Most backups occur when water is being used in the house and isn’t able to drain out of your building drain fast enough.  Think of your plumbing like a funnel. If you were to pour water into a funnel too quickly, it would overwhelm the opening and backup – or overflow.  If the opening of the funnel was clogged with debris, the water you poured in would backup even faster. In your sewer’s case, if a clogged pipe is impeding the flow of water or you are draining too much water too quickly, you are at risk of a sewage backup.  

The pipes in your home’s building drain system are sized and installed in a way that backups shouldn’t occur under normal conditions. As long as your home’s plumbing was installed to a plumbing code standard, it follows a system of “DFUs.” Drainage Fixture Unit Values – or DFUs – have been determined by the Uniform Plumbing Code to determine how much water volume your sewer and drains can handle.  This means that every pipe is sized to handle the discharge of each plumbing fixture connected to that section of pipe. Even if you were to use every toilet, shower, sink, etc at the same time, your plumbing is meant to handle that water without backing up.  That is, unless something is wrong.

If you notice sewage flooding up from a drain or toilet, stop the immediate use of water.  Simply stopping water usage for a brief time will stop the backup in this instance. Keep the dishwasher and washing machine from draining.  Stop the long showers. Space out these uses of water and give your pipes some time to slowly drain off until a plumber can come and diagnose the underlying problem.

What if the problem doesn’t stop when you cut off the water drainage?  In our case a few weeks ago, the sewage backup was the result of a problem in the county sewer main. Even though we weren’t using any water in our home and no matter what appliances we shut down, the entire neighborhood’s wastewater continued to flood into our basement.  If this is the case for you, immediately call the municipality and/or a plumber. While waiting for help to arrive, try to salvage as many of your possessions before they are touched by sewage. Try to save irreplaceable items first, such as photo albums or family heirlooms that would otherwise be ruined.

Who should I call when my sewer backs up?

As mentioned above, if you can’t stop the sewage backup, you need to call the municipality and/or your trusted plumber.  In Baltimore City and Baltimore County, your home must have an exterior cleanout at your property’s edge for the municipality to help you.  If the city/county can’t assist you because you don’t have an exterior cleanout, call a licensed plumber.  Unfortunately there is not much you can do without the tools and plugs you need immediately on hand when a blockage is off your property.

If sewer backups are a frequent recurring issue in your home, you should call a plumber for a diagnosis and plan of action.  Even if the problem is off your property, having a plumber involved can often speed up the resolution of your problem. Often, a plumber can provide you with proof that the sewer problem is not on your property.

How to clean up a sewage backup

Cut off electrical power to the area

Most sewage backups occur in basements or the first floor of homes.  These spaces have outlets, appliances, lights, wires, etc that pose an electrical hazard during flooding.  Before entering the damaged area, the electricity should be shut off. If the power can be turned off to the affected area, do not endanger yourself by entering the area.

Stop water use

As mentioned at the outset of this article, continued water use during a backup can worsen the problem.  Stop running your dishwasher, washing machine, sinks, and showers until the problem is resolved.

Put on personal protective gear

There are many harmful things in sewage, from bacteria to dangerous objects that may have been sent down the drain.  Personal protective equipment should be worn when entering the area where the backup occurred.  Safety glasses, rubber gloves, rubber boots, and a face mask can help keep you safe from the viruses, bacteria, and overall gross contents of the sewage.

Take photos or video documenting the damaged area

Before cleaning up, it would be wise to take some photos or a video of the area damaged by sewage.  This documentation is handy for showing your insurance company the extent of the sewage backup. It is also a great way to show any of your possessions that may have been damaged during the flooding.  Proof of damage and destruction may help toward the replacement or reimbursement of your damaged property.

Dispose of any damaged property

Inevitably, some of your belongings will be ruined from the sewage backup.  Carpet, boxes, clothing, books … anything that can’t be easily disinfected should be thrown away.  Truth be told, you may want to get rid of more than you think you should. Be generous with what you think was damaged.  You don’t want mold to occur because you didn’t remediate enough. Possessions that are soiled but can be cleaned should be thoroughly sanitized.

Clean up and dispose of wastewater

Time for the fun part.  Cleaning up the sewage may seem like a daunting task.  A few helpful tools to have on hand are a wet/dry vac, a push broom, a mop, a 5 gallon bucket, and bleach.  Vacuum up as much of the waste as you can with the wet/dry vac. Check with your municipality about where they recommend for you dispose of this wastewater.  The push broom is helpful for moving all of the waste to a central part of the room for easier vacuuming. Once the liquid and large solids have been disposed of, it’s time to disinfect.  Mix the bleach with water in a 5 gallon bucket according to the manufacturer’s instructions. Use the bleach solution to mop or douse the floor and walls (if unfinished). You may find it beneficial to vacuum again.  This is a long process but it is imperative that the viruses and bacteria spread by the sewage be killed.

Mold prevention

Spraying a fungicide and antiviral is a good idea.  Any organic surfaces like wood or fabric are liable to growing mold after the flooding.  Be generous with how much you spray.

Run a dehumidifier

Once the area is cleaned up, it would be wise to run a dehumidifier.  This works best when placed centrally in the room and used in conjunction with box fans to provide airflow.  This combination helps ensure that your floors and walls dry out, in addition to any other surfaces and objects in the area that have become damp.  Thorough drying can help prevent mold from growing. Ventilating the area is a good way to get rid of the sewage odor as well.

Depending on the severity of the sewage backup in your home, you may want to submit an insurance claim. Taking photos as mentioned in the steps above is a helpful tip if this is the route you choose. If the damage is extensive, your insurance company will recommend a restoration and remediation service. If you decide that the DIY cleanup method isn’t for you, and your insurance doesn’t cover the sewage backup, you may still want to hire a professional. Look for a well reviewed and accredited water and mold restoration company. They will handle all cleanup and remediation … for a price.

Sewage backup prevention

After enduring a sewage backup, it isn’t surprising that you never want a repeat occurrence.  So how can you prevent sewer clogs and plumbing backups? There are a few different steps to keep your drains healthy and your wastewater flowing OUT of your home

  • Annual Plumbing Inspection

Having a licensed plumber inspect your home’s drains and plumbing once a year is a great preventative maintenance tactic.  C.A. Taciak & Sons offers annual inspections to our Baltimore area clients. You can get more information here.

  • Drain Cleaning

Some clogs are a one time issue.  It could be something as simple as a toy accidentally flushed down the toilet.  Other clogs are chronic. Root intrusion, sediment buildup, or defects in the pipe can catch sewage and toilet paper, creating a blockage.  Drain cleaning should be done by an expert plumber. You can research a C.A. Taciak & Sons drain clean here.

  • Backwater valve installation

Backwater valves are a surefire way to ensure that the sewage from the municipal sewer main cannot backup into your home.  Check out this article explaining backflow prevention techniques here.