Seasonal

Tree-Root Season: Why Sewer Clogs Peak in Indianapolis Now

By Indianapolis Sewer Line Repair · September 11, 2026 · 7 min read

It is mid-September, the lawns north of 38th Street are brown, and root-clogged sewer lines back up more this month than in any other. That is not a coincidence, and it is not because the roots grew faster in summer. It is because the soil dried out.

The August effect

A tree's fine roots go where the water is. Through spring and early summer, Marion County's glacial clay loam holds plenty of it and roots spread through the whole root zone. By August, after six weeks of 90-degree days and an inch of rain, the top three feet of soil are dry and hard. The one reliably wet place in the yard is inside the sewer lateral.

So the tree concentrates its new fine-root growth at the open clay joints where it can get water, and a joint that had a few root hairs in June has a mat by September. Add the extra load from a house full of people home for Labor Day and the first backup shows up. Then the fall rains start, the combined sewer surcharges, and a lateral that was half-blocked with roots backs up completely.

That is the root-clog calendar here: quiet in April, busy in August, busiest in September and October, quiet again by December when the trees shut down.

Early signs this month

Roots rarely block a line overnight. In September they tend to announce themselves in small ways first:

• The toilet takes a second flush more often than it used to.
• The basement floor drain gurgles when the washer drains.
• The tub drains slowly, even after you clear the hair from the stopper.
• Water rises in the floor drain for a moment during a big load of laundry, then goes down.

Any one of those is worth a note on the calendar. Two of them in the same week is worth a call.

Where it hits hardest

• The silver-maple streets of the postwar west and east sides — Eagledale, Warren Park, Devington — where the trees are 60 years old and the laterals are clay or Orangeburg.
• The pin oak blocks of Meridian-Kessler and Butler-Tarkington, where the root plates are bigger than the front yards.
• Anywhere along Fall Creek, Pleasant Run and Pogues Run, where sycamores and cottonwoods grow in the wetter ground and reach further in a dry year.

Newer PVC laterals in Fishers, Avon or the north half of Carmel don't have the joints for this. The season passes them by.

What to do this month

If you have had a root clog before: this is the month to jet, not December when it backs up during a holiday dinner. A hydro jetting pass in September strips the summer's growth and buys the winter. If the camera shows the pipe is sound, that may be all you need until next fall.

If drains are slow but not backed up: get a camera run now, while the ground is soft and a repair is a one-day job. The camera inspection post covers what to expect.

If it is backing up: stop running water, don't flush, and call a sewer contractor. A cable machine gets the house working today; the jetter and camera come next.

If this is the second or third year in a row: stop paying for jetting. Roots come back because the joints are open, and the permanent fix is a liner that seals them from the inside, or a spot repair if one joint has actually broken. September is a good month for lining too — the resin cures faster in warm pipe.

What not to do

Don't pour root killer down the toilet in September. Copper sulfate and foaming herbicides kill root tips in the pipe for a few months, do nothing to the joint, are hard on the tree, and on the old side of town they go straight into a combined sewer that discharges to the White River in a storm. A jetting pass does more and does it cleanly.

Don't let anyone quote a replacement from the driveway. A root clog is not a diagnosis; it is a symptom. The pipe behind the roots might be fine, might have one bad joint, or might be Orangeburg. The camera tells you which, and the cost ranges from $400 to $15,000 depending on the answer.

What a fall root visit should include

A fall visit for a rooted clay line is usually two parts. First, hydro jetting at about $350–$800 to cut the roots off the wall and flush them to the main. Second, a camera run at about $250–$500 to see the joints once they are clean. Some companies price them together; ask. What you should leave with:

1. A line that drains freely.
2. A video of the clean pipe, with the rooted joints and their footages.
3. A plain answer on whether any joint is broken, not just open.
4. A rough idea of when the next cleaning will be due.

Questions to ask when you book

• Will you jet the line, or only cable it?
• Is a camera run included after the cleaning?
• Can I keep the video?
• If a joint is broken, will you mark it on the lawn?
• What is the price if the line has to be reached through a toilet?

When rain arrives on a rooted line

The first big fall storm is when a lot of rooted lines give up. Two things happen at once. Roots have narrowed the pipe all summer. Then rain raises the water level in the sewer, and on the old side of town the combined main can surcharge. A line that drained fine with half its width open now has nowhere to send the water.

If your floor drain backs up during the first heavy rain of fall, it may be the combined sewer, the roots, or both. Watch what happens after the rain stops. If the water goes down within an hour or two and doesn't come back, the main was likely the cause. If the drain stays slow on a dry day, the roots in your own line are the bigger problem.

Keep a simple root log

Write down each visit: the date, what was used, what the camera showed, and the cost. After two or three entries the pattern is clear. If the gap between cleanings is getting shorter, the joints are opening, and a liner is likely the cheaper path over the next ten years. If the gap holds steady, a cleaning each fall may be all the line needs.

A short timeline for the rest of the year

The fall checklist is the next thing to read if you want to get ahead of the frost, and the maintenance schedule sets out how often a clay line under a big tree should be looked at over the long run. The root mechanics post explains which trees and which pipes are the worst pairing.

Common questions

Is it too late to jet the line in October?

No. October is still a good month, because the roots are at their thickest and the ground is soft if a repair turns up. The main reason to go early is to get ahead of the fall rains and the holidays, when a backup is most inconvenient.

Do roots stop growing in winter?

Mostly. Trees go dormant and root growth slows to almost nothing once the soil cools. The roots already in the pipe stay there, though, so a line that was half blocked in October is still half blocked in January.