This article describes how we identify the main building drain and how we find where it exits the building.

Our page top photo illustrates what a typical main building drain exit point will look like at the foundation wall.

We present an actual case study, illustrated with photos of each step in the diagnosis and replacement of a blocked sewer line.

Guide to Locating the main drain exit point from the building

By simple visual inspection, following the pipes in the home, we could see two interesting facts: first a main drain and cleanout were located in the house rear foundation wall, and second, the toilet drain passed separately through the same rear foundation wall just a few feet away.

While we never bet big on where buried drain lines run, the geometry of the basement of this home made for a small, cramped space.

It seemed likely to us from the angle of the pipes and the ultimate destination of the piping (a septic tank downhill in the rear yard), that the two lines joined outside the home, near the house rear wall, using a wye connector. (That later proved to be the case.)

Bottom line: follow the building drains that you can see, sloping downwards until you find the main drain exiting typically at a building wall or floor.

If you don't have visual access, such as if all of building interior surfaces, walls, ceilings, floors, are finished, then using a drain line inspection camera or drain tracing tools can still find the location of drain lines in your building.

See SEWER / SEPTIC PIPE CAMERAS - find the condition of the drain line and find the point(s) of & distance to drain line elbows, bends, or damage or blockage.

and DRAINFIELD PIPE LOCATION, PRECISE  - tools to trace drain pipes in a building or underground

More examples of how to find where a main drain exits the building are

at FIND MAIN WASTE LINE EXIT for septic tank location or repair

...

Continue reading  at USE a POWER SNAKE to CLEAR a BLOCKED DRAIN or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• SEWER LINE REPLACEMENT - home
  • DIAGNOSE a BLOCKED DRAIN
  • WHEN to CALL a PLUMBER
  • FIND the MAIN BUILDING DRAIN
  • USE a POWER SNAKE to CLEAR a BLOCKED DRAIN
  • FIND DISTANCE to DRAIN BLOCKAGE
  • DETERMINE NEED for DRAIN LINE REPLACEMENT
  • REPLACE SEWER LINE, STEP BY STEP
  • MAKE OTHER SEPTIC REPAIRS
  • INSTALLING the NEW SEWER LINE
  • BED the SEWER LINE in SAND
  • FINAL BACKFILL SEWER LINE TRENCH
  • DOCUMENT BURIED COMPONENT LOCATION
  • FINAL SEEDING & RESTORATION
  • SEWER / SEPTIC LINES at STEEP SITES
• SEPTIC TANK, HOW TO FIND - home

Suggested citation for this web page

FIND the MAIN BUILDING DRAIN at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to DRAIN SEPTIC SEWER PIPES

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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