Lay-flat hose running into an open manhole

Lay-flat hose running into an open manhole. Illustrative only: this photo is not from a job tied to this site or a specific address.

Older south end versus newer north end

Newer north Thornton homes

  • PVC laterals with glued joints that resist roots
  • Deeper basements, often finished by owners after purchase
  • Sump pits for groundwater in many homes
  • HOAs with covenants and sometimes shared amenities

Older south Thornton homes

  • Clay or cast iron laterals with many joints
  • Smaller or partial basements
  • Sump pits less common
  • Mostly no HOA

What causes backups in new construction

A plastic lateral removes the most common long-term cause of backups in older neighborhoods, but it does not stop household clogs. Wipes and grease catch on any imperfection, including a fitting at the foundation or a cleanout. In the first years after construction, debris left in the line by builders, such as drywall mud, grout or packaging, can also restrict flow. Settling soil around new foundations can create a slight sag in a lateral that was laid on fresh fill.

The other new-home issue is sump discharge. Many basements north of 120th Avenue have sump pits that collect groundwater from around the foundation. If an owner or a finisher routes the sump discharge into a floor drain or laundry sink, every heavy rain sends groundwater into the sanitary line, where it does not belong. Ask the city what is permitted and keep that discharge outdoors.

New-home owner checklist

  • Locate the sewer cleanout and the sump pit, and know which is which
  • Confirm the sump pump discharges to the yard, not to an interior drain
  • If you finished the basement, check that the floor drain was not covered or boxed in
  • Keep basement bathroom fixtures in use or refill traps on a schedule
  • Ask your agent whether your policy covers sewer backup and sump overflow separately
  • Read HOA documents for anything about shared utilities in attached homes

Questions for a plumber in a newer home

  1. Is there any construction debris in the line on camera?
  2. Does the lateral have consistent slope, or is there a low spot near the foundation?
  3. Would a backwater valve fit, given where the line leaves the house?
  4. Is the floor drain trap and any basement bath properly vented?
Map of North Thornton. It shows an area, not an office or a job site.

General information for Thornton, not a quote or professional advice. In an emergency, call 911.