Best Practices for Septic Tank Abandonment

Precautions must be taken to render the area of the old tank safe and free of environmental or public health impacts

Best Practices for Septic Tank Abandonment

A steel tank that's being abandoned during a system repair.

Interested in Onsite Systems?

Get Onsite Systems articles, news and videos right in your inbox! Sign up now.

Onsite Systems + Get Alerts

In the event that a septic tank is no longer used (because of an alternate connection to city sewer, tank replacement during system upgrade or repair, etc.), the tank must be properly abandoned. This applies to old cesspools, leaching pits, dry wells, seepage pits, vault privies and pit privies. Access for future discharge to the system must be permanently denied. This can be accomplished by removing the piping or filling the end of the supply pipe with grout.

Local codes may list specific requirements for this activity and must be followed. In the absence of specific code requirements, the following procedures are recommended. The goal is to render the area of the old tank safe and free of environmental or public health impacts.

The tank must first be completely emptied of its contents using a vacuum truck operated by an appropriately licensed professional who will properly dispose of the septage. Three common processes for dealing with the empty tank are:

  1. Remove and dispose of the tank at an approved site (normally a landfill).
  2. Crush the tank completely and backfill. The bottom must be broken to ensure it will drain water.
  3. Fill the tank with granular material or some other inert, flowable material such as concrete. The abandoned tank must present no collapse or confined-space hazard. 

If the soil treatment and dispersal systems are removed, contaminated materials shall be properly handled to prevent human contact. Contaminated materials include distribution media, soil or sand within approximately 3 feet of the system bottom, distribution pipes, tanks and contaminated soil around leaky tanks. Contaminated material also includes any soil that received sewage from a surface failure. Inspection pipes can be removed, backfilled and disposed of in a mixed municipal solid waste landfill.

Typically, the soil treatment area is left in place; but if it’s removed, precautions must be taken to prevent human contact with the contaminated materials. Contaminated soil material may be stockpiled prior to final disposal to allow time for pathogen die-off. The stockpiling site must meet all the separation distances for a septic system, including well and property line setbacks and your vertical separation distance to saturated soil or bedrock. Additionally, the stockpiled material must be covered with a minimum of 6 inches of uncontaminated soil and be protected from erosion. The local unit of government should be contacted for any additional or stricter ordinance requirements.

If contaminated material is to be spread or used on site within one year of contact with sewage, the material should be placed in an area meeting the soil and setback requirements of septic systems in your state code, and it is wise to cover the material with a minimum of 6 inches of uncontaminated soil and protected from erosion. Contaminated pipe, geotextile fabric or other material must be dried and disposed of in a mixed municipal solid waste landfill.

All electrical devices and devices containing mercury must be removed and disposed of according to applicable regulations. The pump tanks are abandoned similarly to other tanks as described above. All the components must be removed before backfilling. If the old floats were mercury floats, these must be handled as a hazardous material. Be careful that the mercury vial is not broken during the process. All the wiring should be removed; the conduit can be left buried but should be capped. 

About the Author: Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation, and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association and the National Onsite Wastewater Recycling Association, and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system maintenance and operation by sending an email to


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.