CT ECO Basic Data Guide

Soil Potential Ratings for Subsurface Sewage Disposal Systems

Example of Potential Subsurface Sewage Disposal Systems


The Soil Potential Ratings for Subsurface Disposal Systems data indicates the relative suitability of soils for installing a single family residence subsurface disposal system (SSDS), as well as ways those limitations may be overcome. For additional documentation including a description of the map legend for Potential Subsurface Sewage Disposal System, refer to the CT ECO Complete Resource Guide for Potential Subsurface Sewage Disposal System.

All soil information included in the CT ECO maps and map viewers is from the Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS), which is based on information originally published on the set of Soil Survey quarter quadrangle maps that cover Connecticut.


Soil potential ratings are classes that indicate the relative quality of a soil for a particular use compared to other soils in a given area. These soil potentials were developed for planning purposes and are not intended as recommendations for soil use. The special requirements identified to overcome soil limitations are a guide to planning and are not to be applied at a specific location without on-site investigation for design and installation. SSDS are systems consisting of a house sewer, a septic tank followed by a leaching system, any necessary pumps and siphons, and groundwater control system on which the operation of the leaching system is dependent. This interpretation focuses mainly on the septic tank leaching field and groundwater control system. A typical SSDS is assumed to be for a single family, 4-bedroom home on a 1-acre lot with a private well, or a ½-acre lot with public water supply. The system has a 1250 gallon septic tank and a 660 to 1000 square foot leaching field. This interpretation identifies the soil characteristics that are present in order for a typical system to be constructed.

Use Limitations

This data set is not designed for use as a primary regulatory tool in permitting or siting decisions, but may be used as a reference source. This is public information and may be interpreted by organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions that they make. The Natural Resources Conservation Service will not perform any evaluations of these maps for purposes related solely to State or local regulatory programs.

Dataset Information

  • Status - This information is updated as needed. The previously published county soil surveys (published between 1962 and 1981) are superseded by this official soil information. County soil surveys are for historical use only.
  • Date of Data - The original data was collected from published surveys from 1962 to 1981, field mapping from 1985 through 2001 and additional attribute documentation to 3/23/2007.
  • Map Scale and Accuracy - 1:12,000 (1 inch = 12,000 feet). Minimum delineation is 3 acres in size.

Additional Documentation

  • Soil Potential Ratings for Subsurface Sewage Disposal Systems - CT ECO Complete Resource Guide
  • Soil map unit GIS Metadata – Contains technical documentation describing the Soil map units data and the data sources, process steps, and standards used to collect, digitize, and store this information in a geographic information system (GIS).
  • Soil interpretation GIS Metadata – Contains technical documentation describing the data table that defines soil interpretation such as Hydric Soils, Inland Wetland Soils, and Potential for Subsurface Disposal Systems. This lookup table is related to the soil map unit data and used to create the various soil interpretations included in CT ECO.
  • Soil Potential Ratings for Subsurface Sewage Disposal Systems for Single Family Residences Additional information regarding the evaluation criteria, corrective measures, and specific site conditions may be found in the document.


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