Sewer Backup in New York City, NY: Causes & Fixes

Why is sewage backing up into my New York City home?Sewer backups in New York City usually have one of two causes: a blocked private house sewer — often at the house trap, an old clay connection or root-filled pipe under the sidewalk — or combined sewers overwhelmed by intense rain. Which one it is decides the fix, so start by noticing when backups happen: dry weather points to your line; storms point to the public system.

Act now

A sewage backup is an emergency: it spreads quickly, contaminates everything it touches and gets worse every time a fixture is used.

Call (866) 417-0220

Why it happens in New York City

Blocked house trap

The running trap near the front wall of many older buildings catches debris and is a frequent backup point.

Combined sewer surcharge

Cloudbursts fill combined sewers and push water back up into the lowest drains, as seen during the remnants of Hurricane Ida in 2021.

Root-damaged clay connection

Street tree roots enter older clay house sewers under the sidewalk.

Shared building stacks

In multi-family buildings, a clog in a shared stack can surface in the lowest unit.

Signs to watch for

Dirty water rising in a basement floor drain
Sewage in a tub or shower when a toilet is flushed
Several drains gurgling or slow at once
Water coming out of the main cleanout
Sewer odor in the lowest level of the home

Emergency, or can it wait?

Call right away if…

Sewage in living space
Backup affecting all drains
Backup during a storm that keeps rising

Usually OK to schedule if…

A single slow drain with no sewage
Occasional gurgling with normal flow

What New York City homeowners can check first

Does it happen in dry weather or only during heavy rain?
Is the house trap cleanout accessible in the basement?
Are other units in the building affected?
Is there a backwater valve on your sewer line?

Unfinished basement with exposed pipes — Stock photo: Oleksandr Chernobai / Unsplash

How our plumbers fix it

Open the cleanout to locate whether the blockage is inside or outside the house.
Clear the main line with a cable machine or jetter.
Run a sewer camera to find roots, breaks or sags.
Check for a missing or failed backwater valve if backups follow storms.

Sewer Backup in New York City: questions

Can the city help if my basement floods with sewage during a storm?

If the public sewer caused it, you can report it to 311 and the Department of Environmental Protection. Damage claims and insurance depend on circumstances and your policy.

Does a backwater valve stop storm backups in NYC?

A properly installed backwater valve stops sewage from flowing back into your building when the public sewer is surcharged. Installation should be done by a licensed plumber with the required filings.

Why does sewage come up in my basement floor drain?

The basement floor drain is the lowest opening, so it’s the first place water appears when the house sewer or public sewer is blocked.

Next steps

Main Sewer Line CleaningThe main sewer line carries all of a home's wastewater to the city sewer or septic tank.Sewer Line Repair in New York CitySewer line repair fixes damage to the building sewer or lateral, the pipe that carries wastewater from a house to the public sewer main or septic system.Sewer Camera InspectionA sewer camera inspection sends a waterproof camera on a flexible push rod through the sewer lateral to record its condition.Hydro JettingHydro jetting cleans drain and sewer lines with water at high pressure, delivered through a hose with a nozzle that has rear-facing jets.Emergency Plumbing in New York CityEmergency plumbing is urgent repair work for a problem that is actively causing water damage, a sanitation hazard, a gas risk or a total loss of water or drainage in a home.

National guide: Sewer Backup · Plumbing in New York City