Main sewer line problems develop from a handful of predictable causes — tree root intrusion, aging or corroded pipe material, grease and debris buildup, and ground movement that shifts or cracks the line. In Denver and the broader Front Range, expansive clay soils are a significant contributing factor: as the soil swells with moisture and contracts during dry spells, it exerts lateral pressure on buried sewer pipes that eventually leads to misalignment, bellies (low spots where sewage pools), and cracks. Understanding what is working against your sewer line is the first step toward preventing a messy, expensive failure.
Tree Root Intrusion
Roots are the number-one cause of sewer line damage in established neighborhoods. Tree roots follow the path of least resistance toward moisture and nutrients, and even a hairline crack or a loose pipe joint is enough of an invitation. Once inside, roots grow rapidly, eventually forming a root mass that snags toilet paper and waste, causing slow drains, gurgling, and full blockages. Cottonwood, willow, and silver maple — all common along Front Range properties — are notorious for aggressive root systems. Even smaller ornamental trees planted near your sewer lateral can cause problems within a few years.
Aging and Corroded Pipe Materials
The material your sewer line is made of has a lot to do with how long it lasts and what kind of problems it develops. Homes built before the 1970s often have clay tile sewer lines, which are prone to root intrusion at the joints and become brittle over time. Cast iron lines from the mid-20th century corrode from the inside out as hydrogen sulfide gas produced by sewage reacts with moisture and pipe walls. Orangeburg pipe — a tar-and-fiber composite used from the 1940s through the 1960s — is particularly prone to delaminating and collapsing under soil pressure. If your home was built before 1975 and the sewer line has never been inspected or replaced, it is worth scheduling a camera inspection to understand what you are working with.
Grease, Scale, and Solid Buildup
Even modern PVC sewer lines develop problems when grease, soap scum, and non-flushable wipes accumulate on the pipe walls. Cooking grease is liquid when it goes down the drain but solidifies as it cools, building up a sticky layer that catches everything that follows. Denver’s hard water accelerates this process — mineral scale from calcium and magnesium deposits can narrow pipe diameter over years of use. Baby wipes, paper towels, and so-called “flushable” wipes do not break down in the line and are a leading cause of blockages that require professional clearing.
Ground Movement and Soil Conditions
Colorado’s expansive clay soils are hard on underground infrastructure. When heavy spring rains saturate the soil, it expands; during hot, dry summers it shrinks back. This repeated cycle shifts the ground around your sewer pipe, causing joints to separate, pipes to belly downward, or sections to crack entirely. Homes near areas with fill soil — common in newer subdivisions — face additional settling risk. A belly in the line creates a permanent low point where solids accumulate and standing water never fully drains, which accelerates deterioration and creates chronic blockage problems.
- Tree root intrusion at pipe joints or cracks, especially under mature trees
- Aging pipe materials — clay tile, cast iron, or Orangeburg that have reached end of service life
- Grease and wipe buildup narrowing the pipe over time
- Expansive clay soil movement causing bellies, joint separation, and cracks
- Ground settlement in newer subdivisions built on fill soil
When to Call Done for a Sewer Line Evaluation
Slow drains throughout the house, sewage odors indoors or in the yard, wet patches over the sewer line, or toilets that gurgle when you run a sink are all warning signs that something is wrong with your main line — not just an individual fixture drain. The most reliable diagnostic tool is a sewer camera inspection, which lets a technician see exactly what is happening inside the pipe without any digging. If roots, corrosion, or a belly are confirmed, Done can recommend the right repair path — from hydro jetting to clear roots and buildup, to trenchless pipe lining for structural repairs that do not require excavating your yard.
If you are seeing any of the warning signs above, do not wait for a full backup — reach out to Done to schedule an inspection and get a clear picture of your sewer line’s condition before a small problem becomes a large one.
