Septic or sewer line exiting a buildingStart Here to Find The Septic Tank: The Sewer Line Exit Point
a clue to locating the septic tank

  • FIND MAIN WASTE LINE EXIT - CONTENTS: Start your search for the septic tank by finding the point where the main waste line leaves the building. How to locate the septic tank at a property, a detailed, step by step procedure to find the septic tank, distribution box, and leach field.
  • POST a QUESTION or READ FAQs about finding where the sewer or septic main drain line exits the building - a pointer to possible septic tank location

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

How to find the septic tank:

To start your outside search for the septic tank, locate point at which the main sewer line leaves the building.

The main waste line exit point at a building often points to the direction and sometimes right to the septic tank. But there are exceptions, as we explain here. Septic tank location guide: this document provides suggestions and procedures for finding a septic tank.

Green links show where you are. © Copyright 2017, All Rights Reserved.

FIND MAIN WASTE LINE EXIT - How to Find the Septic Tank by First Looking Inside the Building

LARGER IMAGE: note the main waste line leaving in the basement far corner?

When the septic tank needs to be pumped, a regular maintenance task, the cost of that service will be less if the property owner found the septic tank location and perhaps even uncovered the septic tank pumping access cover.

Other reasons to find the septic tank include inspecting and testing septic systems when buying a home or for safety, to assure that the septic tank cover is in good condition. This article tells us how to locate a septic tank when it's placement is not already known or when the location of the septic tank is not visually obvious.

Videos showing how to find the septic system, septic tank, & septic drainfield are at SEPTIC VIDEOS. Also see SEPTIC DRAINFIELD LOCATION - how to find the leach fields. If there are no obvious clues outside that clearly mark the location of a septic tank, we can find some critical clues about septic tank location by looking inside the building. Here they are:

Find the main waste line exit point

Look in the lowest level of the building such as basement or crawl space to see where the Main waste line exits the building. The line from house to tank begins outside the house wall at this same point.

Main Drain Single Exit Point

Usually, inside the building the waste drain lines run to a single exit point at the building wall or in the building lowest level floor or crawl space. In the photo above you can see the main sewer line leaving the building low on the wall near the basement corner.

In the photo at the top of this page we have located a sewer line where it leaves the basement wall. Just outside we would expect to find this same sewer pipe. From that point the buried main drain line connects the building to its septic tank.

Particularly for sites where there are not obvious outside clues, this is where to begin your search for the septic tank - inside the building, following its drain lines.

Outside Septic Waste Line Vents Can Point to the Septic Tank Location

At some buildings you may see a 4" to 6" diameter vertical pipe rising from the soil near the house wall, often with a mushroom-shaped cap on top, or you may see such a pipe protruding horizontally through the building foundation wall and extending for a few inches, covered by a cap or by a perforated cover. Sewer line vents are often vents installed on the main waste line.

Finding one of these sewer line vents in a building wall or protruding from the soil outside is another way to spot where the main waste line is exiting the building.

Septic Tank Location Articles


Continue reading at POSSIBLE SEPTIC TANK LOCATIONS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

FIND MAIN WASTE LINE EXIT at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman