A line nobody has seen in a hundred years
The sewer service line, often called the lateral, carries everything from your house to the public main. In many homes built around the park in the early 1900s it is vitrified clay pipe laid in short sections, sometimes joined to a cast-iron segment where it leaves the foundation. Clay itself lasts a long time. The weak points are the joints, which were packed with mortar or simply butted together, and any spot where the soil has settled and left a belly in the line.
Roots from elms, maples, cottonwoods and other mature trees find the moist, nutrient-rich air leaking from those joints. Hair-thin roots grow into the pipe, thicken, and form a mat that catches paper and grease. For months nothing seems wrong. Then a heavy laundry day or a holiday houseful of guests sends more water down than the narrowed pipe can carry, and it comes back up through the lowest drain in the basement.
In Denver, the property owner is generally responsible for the sewer service line, including the part under the parkway and street in many cases. Confirm the details for your address with the city before assuming who pays for what.
Signs the lateral is the problem
- Gurgling
- Toilets or the basement drain gurgle when the washing machine empties
- Slow everything
- Several fixtures drain slowly at once, not just one sink
- Ring at the drain
- A dark stain or debris ring around the basement floor drain
- Timing
- Backups follow heavy water use rather than storms
- History
- A previous owner had the line cleared, sometimes more than once
Common fixes and what they involve
- Option
- Root cutting (rodding or jetting)
- What it does
- Clears roots and debris from inside the pipe
- Things to weigh
- Restores flow but roots regrow; often becomes a recurring service
- Option
- Spot repair
- What it does
- Excavates and replaces one damaged section
- Things to weigh
- Useful when one joint or belly causes the trouble; digging near tree roots and sidewalks needs care
- Option
- Pipe lining
- What it does
- Cures a new liner inside the old pipe without a full trench
- Things to weigh
- Needs a pipe that is still round enough to line; ask about the connection at the main
- Option
- Full replacement
- What it does
- Replaces the lateral with modern pipe
- Things to weigh
- Most disruptive; may involve the parkway, sidewalk or street and a city permit
- Option
- Backwater valve
- What it does
- Lets water out but closes if the main surcharges
- Things to weigh
- Helps with city-side backups; does not fix roots in your own line
Which option fits depends on what a camera inspection shows. Ask a licensed plumber or sewer contractor to explain the footage with you.
Before you choose a repair
- Get the camera inspection recorded and ask for a copy of the video with distance markings.
- Ask where the cleanout is, or whether one should be added near the foundation for easier access.
- Find out whether the work requires a permit from the City and County of Denver and who pulls it.
- Ask how the contractor will protect the roots of a street tree; Denver's forestry office may have rules about work near public trees.
- Request at least two opinions if the recommendation is full replacement.
General information for Washington Park, not a quote or professional advice. In an emergency, call 911.