Tree Roots in Your Sewer Line: Signs, Costs, and Fixes

Why do tree roots get into a sewer line in the first place?

Warm wastewater moving through a buried pipe gives off vapor. That vapor escapes through hairline cracks and loose joints into cooler soil, and roots follow it straight back to the opening. Once a root tip finds a gap it keeps growing, thickens, and pries the joint wider. What starts as a few hairs turns into a mat that catches paper and grease until the line stops draining.

Older pipe is the target. Clay and cast iron laterals were laid in short sections with a joint every few feet, and every one of those joints is a possible door. Plenty of housing in Santa Rosa, Petaluma, San Rafael, and the older parts of Rohnert Park still runs on that pipe. A review published through the USDA Forest Service reports that roots cause more than 50 percent of all sewer blockages, and that old jointed pipe, shallow pipe, and small diameter pipe carry the most risk. Read the study summary.

Distance matters less than people expect. In the survey behind that review, 48 percent of root intrusions traced to a tree less than 10 feet from the pipe, and another 44 percent to a tree 10 to 20 feet away. A liquidambar out at the curb can still reach your lateral.

What are the signs roots are in your sewer line?

• Slow drains in more than one fixture at the same time, usually the lowest ones in the house first.
• A toilet that gurgles or drops its water level when the washing machine drains.
• The same line clogging every few months no matter what you pour down it.
• A strip of lawn over the lateral that stays green and soft all through August.
• Sewage smell in the yard or the crawlspace.

One slow sink is a fixture problem. Two or more fixtures acting up together points at the main line. Our write-ups on a gurgling toilet and a main drain backing up walk through how to tell those apart before you call anybody.

Why does late summer matter in Sonoma and Marin?

Two reasons. First, we go months with no rain. From late spring into fall the soil around your lateral dries out, and the steadiest moisture left in the ground is the water inside your sewer pipe. Roots go where the water is. Second, a line that is only partly blocked will limp along all summer on light use, then quit the week the storms start and groundwater begins pushing into the same pipe.

The EPA estimates there are at least 23,000 to 75,000 sanitary sewer overflows a year in the United States, and it lists blockages from roots, grease, and sediment among the main causes. See the EPA overflow FAQ. The ones that reach a homeowner show up as sewage on a bathroom floor.

September is the cheap month to handle this. February is the expensive one.

Do chemical root killers actually work?

Copper sulfate and foaming root products burn back the fine roots the foam touches, and they buy some time in a line that is only lightly invaded. They will not clear a root mass that already fills the pipe, and they do nothing about the crack the roots came through. Check your local sanitation district rules before you put any of it down a sewer line. Treat these products as a maintenance step after mechanical cleaning, not as the repair.

What does root removal cost around here?

Real numbers from our drain cleaning price guide:

• Main sewer line cabling: $250 to $600, with root cutting sitting at the top of that range.
• Hydro jetting a line with heavy roots or grease: $600 to $1,400.
• Camera inspection added to a cleaning: $100 to $300 with an accessible cleanout.
• New cleanout installed: $600 to $2,000, a one time cost that makes every future visit shorter and cheaper.

Cabling cuts a hole through the root mass. Jetting scours the pipe wall, which is what actually buys you time, because it strips the fine roots off the joint instead of punching a channel through the middle of them. On a line with a known root problem we normally jet it, then run the camera, so you can see what you are dealing with instead of guessing.

When do roots mean the pipe has to be replaced?

Roots are the symptom. The pipe already had an opening. The camera is what tells you whether that opening is one bad joint or a lateral that is failing end to end. A single bad section can often be dug and fixed as a spot repair, $1,500 to $4,500 in our sewer line cost guide. A lateral that is offset, bellied, or root bound the whole run is a replacement or a liner, $7,000 to $15,000 for a typical 40 to 80 foot residential lateral, and more when the work goes under a street.

Marin sellers have a second reason to look early. Several Marin districts require a sewer lateral inspection at point of sale, and roots are the most common thing those inspections turn up. The rules are in our guide to Marin County sewer lateral inspections.

How do you keep roots from coming back?

Once a line has roots, it has roots. The joint is still open. What you can control is how often it costs you anything:

• Put a cleaning on the calendar. Every 12 to 18 months on a known root line, timed for late summer, ahead of the rain.
• Get a cleanout installed if there is not one. Every service call after that is faster and costs less.
• Do not plant a fast growing tree within 20 feet of the lateral, and find out where the lateral runs before you plant anything.
• Line or replace the bad section once the camera shows the pipe itself is failing, instead of paying to cable it twice a year forever.

CNTRline has worked Sonoma and Marin sewer lines since 2017, and we run the camera and the jetter ourselves rather than subbing the work out. If your drains are slow or a toilet is gurgling, call (707) 308-5599 for a free quote on drain and sewer cleaning or sewer line repair. If it is already coming back up into the house, that is an emergency call, and we answer seven days a week.