Smoke Testing Sewer Leak: How the Test Finds Open Lines

What is smoke testing for a sewer line?

Smoke testing is a test for the sewer and drain side of a home, not the water supply side. The company seals the line ends, runs a blower that pushes smoke into the pipe, and watches where smoke comes out. Smoke only leaves through an opening, so each plume points to a place where the line is open to air. The test covers the full run in one pass, from the house drains to the yard line, and it finds openings that a camera can miss when the break sits at a joint or a vent. A sewer and drain line check of this kind suits a home where the symptom is a smell or a damp patch near the sewer run, but no break is visible.

How does smoke testing sewer leak work?

The visit starts with a walk of the drains, the cleanouts, and the yard line route. The company caps or plugs the line ends, sets the blower at a cleanout or a vent, and pushes a steady flow of smoke through the pipe. A second person watches the yard, the roof line, and the drains inside while smoke fills the system. Smoke that rises from a roof vent is normal, because vents are open by design and built to release air. Smoke that rises from soil, a driveway seam, a floor drain, or a dry trap is a finding, and each finding gets marked on the ground or noted in the report. The order follows how a detection visit runs on any line type: test first, mark second, open last.

What openings does smoke find?

Four openings show up most often. A crack in the pipe wall lets smoke out along the run, and the plume marks the break point. A joint that separated lets smoke out at the seam, and that seam is the repair point. A trap that dried out lets smoke into a room through a floor drain or a seldom used fixture, and that same opening lets sewer odor into the room. A vent pipe that broke or cracked lets smoke out in a wall or at the roof line. Smoke finds all four in one pass, because the test fills the whole line at once instead of looking at one section at a time.

What does smoke inside the house mean?

Smoke inside means a trap dried out or a drain connection is open. Floor drains in laundry rooms and garages dry out when they sit unused for weeks, and a dry trap is an open door between the sewer line and the room. The company notes which fixture let smoke through, because that fixture is the one to check first. Running water into a dry trap refills it, but a trap that keeps drying out, or a connection that stays open, needs a repair plumber to look at the fitting. The report names the fixture, so the plumber starts at the right drain.

Why does a camera miss some sewer openings?

A camera sees the inside of the pipe, and it shows breaks, roots, and bellies on screen. It misses an opening when the break sits at a joint the camera passes too fast, or when the opening is a dry trap or a broken vent outside the camera run. Smoke fills the whole line at once, so it shows openings the camera run did not cover. The two tests pair well: the camera shows the inside of the line, and smoke shows where the line is open to air. The guide to matching each test to the symptom shows where smoke testing fits next to camera work, and a visit that uses both leaves less room for doubt than either test alone.

Is smoke testing safe for a home?

The smoke used for this test is made for sewer testing, and it is non-toxic. It clears with airflow, and it leaves no stain on walls, floors, or fixtures. The company keeps the flow low, watches each room while the test runs, and stops the blower once the line is full. Pets and plants stay clear of the work area during the test as a plain precaution, and the house airs out fast once the blower stops. The test runs at low pressure and uses no heat or dye, so it puts no strain on old pipes.

Does smoke testing work on old Citrus Heights lines?

Citrus Heights homes are old on average, with a median build year of 1977 and about 40 percent of homes built in the 1970s. Older sewer lines carry more joints, and joints are where separations show up first. Tree roots reach lines through the same openings smoke finds, and a root mass at a joint often marks a break nearby. Smoke testing suits these lines because it checks every joint in one pass instead of opening the yard to look. The test runs the same way across Citrus Heights, Antelope, Carmichael, Fair Oaks, North Highlands, Orangevale, Roseville, and Sacramento.

What happens after smoke testing sewer leak finds an opening?

The company marks the spot and writes the report. The report names each opening, the test that found it, and the repair point. Detection ends there. Your repair plumber opens the marked spot and repairs the joint, the section, or the vent, and a retest after the repair confirms the line holds. The report goes to the plumber with the marks still on the ground, so the opening stays small and the repair crew starts at the right place. A report, repair, and retest order keeps the job in sequence.

What do you get at the end of the visit?

A marked spot for each opening, a written report that names the openings and the tests run, and a plain next step for your repair plumber. That is the close of a smoke testing sewer leak visit: test the full line, mark each opening, report the spots, and let the repair crew work from marks instead of guesses. If no smoke escapes except from the roof vents, the report says so, and the search moves to other causes with the sewer line ruled out. Either way, the visit leaves a written record of what the line showed.

Frequently asked questions

Related

• Sewer and Drain Line Leak Detection, Citrus Heights
• Which Leak Detection Method?
• How Leak Detection Works
• Water Main and Service Line Leak Detection, Citrus Heights
• Contact AquaTrace Leak Detection

Last updated: November 1, 2026.