Setback Distance From Septic to Drinking Water Well

Many rural residents use an on-site wastewater treatment system (an individual septic system) for treatment and disposal of wastewater, or sewage. Household wastewater may contain contaminants such as disease-causing bacteria, infectious viruses, household chemicals, and excess nutrients. A properly designed, installed, and maintained septic treatment system will reduce the risk of polluting the drinking water supply with these contaminants.

State and local codes specify how on-site wastewater treatment systems must be designed, installed, and maintained. A septic tank and soil absorption system is an approved wastewater treatment system in many locations. A residential lagoon may be an approved system in some areas. Alternative technologies also may be allowed.

State and local codes specify minimum separation, or setback, distances from different components of on-site wastewater treatment systems to private drinking water wells. While minimum setbacks reduce the risk of contamination to a private drinking water supply, greater separation distances can often provide better protection. Minimum setback distances are determined with local geology in mind and will vary from state to state or area to area.

Nebraska minimum setbacks will be used as an example. A septic tank in Nebraska must be at least 50 feet and a soil absorption system (leach field or drainfield) must be at least 100 feet from a private drinking water well. A residential lagoon must be at least 100 feet from a private drinking water well. All sewer lines must be at least 50 feet from a private drinking water well. Always check local regulations for minimum setback distances in your area.


For tools and tips on properly maintaining an on-site wastewater system, see the U.S. Environmental Protection Agency’s Septic (Onsite) Systems.