What Is Sewer System Smoke Testing?


Property owners in Oakland and Berkeley may experience “random city smoke testing.” Local ordinances require sewer lines to be tested for code compliance.

What Is Sewer System Smoke Testing?

Underground smoke testing is used to detect deficiencies in sewer pipes and the sewage system. Smoke tests can be especially important after episodes of heavy rainfall. Smoke testing is a low-cost and effective way to identify water infiltration sources, including roof downspouts, yard drains, slab drains, defective connections, and storm water drainage systems.

The cities of Oakland and Berkeley are legally allowed to conduct random smoke tests of residential sewer laterals without permission from homeowners or property owners. Notices are typically delivered by mail a few days before smoke testing. If you do not receive a notice or the notice arrives after testing has been completed, the information below may be helpful.

What exactly is a smoke test? According to the City of Berkeley

“Smoke testing is the industry standard and an efficient, cost effective way to locate and identify leaks and the source of storm water infiltration problems in the sanitary sewer system.”

The reason municipal authorities conduct smoke testing is to identify potential problems within the entire sewer system. Smoke testing identifies sources of leaks or other breaches in a sewer system. Regular testing is conducted to mitigate possible environmental and property damage that can occur when a local sewage system is deluged by rain water.

Smoke tests take place throughout the entire sewer system, which includes the sewer main under the street as well as private sewer laterals that connect homes and businesses to the public sewer system.

How Does Smoke Testing Work?


A smoke test is a sewer inspection method whereby nontoxic smoke is forced into sewer system access points. The smoke makes its way through all connected pipes in sewer system, thereby indicating pipe leaks, breached utility holes, cracks, uncapped lines, and other defects. Testers can also locate unknown pipe sections, such as cleanouts, downspouts, and sump pumps. Certain types of connections may contravene local ordinances.

Regarding the smoke itself, the City of Oakland explains:

“The smoke is nontoxic and nonhazardous and is manufactured specifically for this purpose. It leaves no residuals or stains, and has no effects on plants or animals. The smoke should not enter your home, but if it does, it will have a distinct odor and should only last a few minutes with proper ventilation. Please note, all plumbing fixture drain traps must be filled with water prior to smoke testing.”

Homeowners are requested to pour water down all drains of plumbing fixtures in order to fill the P-traps. This helps prevent smoke from entering the house.

During the smoke test, you may see smoke coming out of grass, utility boxes, cracked pavement, or elsewhere. Each test typically lasts about 15 minutes. Homeowners do not need to be home during testing, although it can be helpful to ensure the home is well-ventilated in case smoke enters the home. Alert the testing crew immediately if smoke appears inside your house.

What Happens After a Smoke Test?

Any pipe system deficiencies are documented in a report that also includes photos of the smoke patterns. Smoke breaches observed on private property will trigger a letter from the city. You will receive and explanation as well as a deadline for correcting the issues, which are the responsibility of the homeowner.

The most common issues require only simple repairs:

  • Disconnecting downspouts from sewer lateral
  • Replacing a missing or broken lateral cleanout cap

However, more difficult mitgation may also be required. Issues that will usually require professional assistance:

  • Cracked sewer laterals
  • Tree root issues
  • Rerouting damage from storm lines

sewer camera inspection is the next step in determining if a more serious plumbing problem exists. Closed circuit TV (CCTV) enables inspectors to examine the extent of the damage. A properly functioning sewage system is critical for the environment in our communities – this helps keep the San Francisco Bay clean, while safeguarding our local ecosystems.


After your home is tested, you will receive communication from the city detailing any deficiencies in your sewer line. (Since most homes in the Bay Area have relatively old sewer systems, most homes will have some sort of deficiency to fix.) It is important to follow the instructions y0u receive and ensure any issues have been remediated by the stipulated deadline.

Our team is happy to help remediate any issues reported in the notification you receive. We also offer video inspection, trenchless sewer repair services, and private sewer lateral replacement. For personal assistance, please contact us at Pipe Spy.