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What to Do During a Sewer Backup (and What Not to Do)
- Oliver Owens
- May 17
- 5 min read
A sewer backup is not the kind of plumbing problem you “power through”
If sewage is coming up through a shower, tub, or floor drain, that’s not just a clogged pipe. That’s your home telling you the main line is blocked and everything you send down the drains has nowhere to go.
This is one of those situations where the first 30 minutes matter. The faster you stop the flow and contain the mess, the less damage you’ll deal with later.
Here’s exactly what to do, what not to do, and when it’s time to call Kramer’s Plumbing.
Step 1: Stop using water, everywhere
This is the big one. If the sewer line is blocked and you keep running water, you’re feeding the backup.
That means:
Do not flush toilets
Do not run showers
Do not run the dishwasher
Do not do laundry
Do not keep testing the sink to see if it drains now
If you have multiple people in the house, tell everyone right away. Most backups get worse because someone unknowingly flushes a toilet or starts a load of laundry.
Step 2: Keep people and pets away from the affected area
Sewage is not just water. It can carry bacteria and other contaminants.
Do this:
Keep kids out of the bathroom that’s backing up
Keep pets away from wet floors
Close doors to contain the area if possible
Open windows for ventilation if the smell is strong
If the backup is in a laundry room or a hallway bathroom, it’s common for it to spread into nearby rooms. The goal is to limit foot traffic so you don’t track it everywhere.
Step 3: If it’s safe, shut off the water to the house
This step depends on the situation.
If you can trust everyone not to run water, you may not need to shut off the main. But if the backup is ongoing, if you have a large household, or if you’re not sure where the water use is coming from, shutting off the main water valve can prevent the situation from getting worse.
If you’re unsure where your main shutoff is, that’s a separate blog we can create later because it’s one of the most useful homeowner topics.
Step 4: Do not use chemical drain cleaners
This is where people accidentally create a dangerous situation.
When the sewer is backing up, pouring chemicals into drains doesn’t fix the blockage. It just creates a pipe full of corrosive liquid that someone has to work around later. It can also splash back.
If you’re dealing with a main sewer backup, this is a mechanical clearing situation, not a chemical one.
Step 5: Contain the water and protect what you can
You don’t need to do a full cleanup before the line is cleared, but you can limit damage.
What helps:
Put towels down to slow spread
Use a wet dry vacuum if you have one and it’s safe to do so
Move rugs and items off the floor
If the backup is near baseboards or cabinets, keep an eye on how far it’s spreading
If sewage has reached carpet or seeped into flooring, clearing the line is still the first priority. Deep cleaning comes after the plumbing problem is fixed.
Step 6: Call a plumber for main line clearing
When sewage is backing up, the right fix is typically:
Find the blockage location
Clear the main line
Confirm full flow is restored
If needed, inspect for the cause so it doesn’t repeat
If the issue is recurring, a camera inspection can be the difference between fixing the symptom and fixing the reason it keeps happening.
What not to do during a sewer backup
Here are the mistakes we see all the time that make things worse:
Do not keep running water to test drains
Do not flush repeatedly to “push it through”
Do not assume it’s only one bathroom if multiple drains are involved
Do not use chemicals
Do not start dismantling traps under sinks if the backup is coming from a main line
Do not ignore gurgling and slow drains afterward, that often means the line is still restricted
Why sewer backups happen in real homes
Most main line backups come from a short list of causes.
Grease and sludge buildup
Kitchen grease is a big contributor. It coats pipe walls and catches debris.
Tree roots
Roots can enter through joints or cracks and create a net that grabs waste.
Flushed items
Wipes, paper towels, and hygiene products commonly contribute to clogs.
Aging sewer lines
Older lines can crack, shift, or develop low spots that collect waste.
What to expect when Kramer’s Plumbing arrives
Most homeowners want to know what happens next, especially in an emergency.
Typical steps:
We ask what fixtures are affected, how long it’s been happening, and if there were warning signs
We locate the best access point, often a cleanout
We clear the blockage using the method that fits the cause
We verify drainage at multiple fixtures
If it’s a repeat issue, we recommend next step options like camera inspection
Our goal is to restore function first, then help you avoid a repeat.
After the line is cleared, what should you do at home?
Once flow is restored, then you can focus on cleaning and prevention.
Basic steps:
Ventilate the area
Remove and bag any heavily contaminated porous items if needed
Clean hard surfaces thoroughly
Wash hands and avoid touching your face during cleanup
If damage is extensive, it may be worth involving a professional cleanup team. That part depends on how far it spread and what materials were affected.
FAQ: Sewer backups
Is a sewer backup an emergency?
Yes. Stop water use and call a plumber right away to prevent damage and contamination spread.
Why is sewage coming up through my shower?
The shower or tub is often the lowest point. When the main line is blocked, backup shows up there first.
Can I still use one bathroom if the other is backing up?
It’s risky. In a main line blockage, any water use can worsen the backup.
Should I turn off my main water valve?
If you can’t control household water use or the backup is continuing, shutting off the main can help prevent further overflow.
Do chemical drain cleaners help?
No. They can make the situation more hazardous and do not clear main line blockages.
How do you prevent sewer backups long term?
Address grease habits, avoid flushing wipes, and if roots or damage are present, get a camera inspection and a real plan.
If the backup stops on its own, am I in the clear?
Not necessarily. A partial blockage can temporarily drain, then back up again. If you had a backup, it’s worth having the line evaluated.
What is the next step if this keeps happening?
A camera inspection to identify roots, pipe damage, or recurring buildup.
Call Kramer’s Plumbing for sewer backup help in Placentia, CA
If you’re dealing with a sewer backup, stop running water and call. We’ll clear the main line and help you understand what caused it so you can avoid repeats.
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