Download the OWTS Permit Application Instructions as a PDF

Permit Types

  • New System: Required for all new construction or new systems installed to serve secondary dwellings, shops, garages, barns, etc., where a sewer connection from a municipality or sewer district is not available within 400 feet.
  • Major Repair: Required for any repair that includes replacement, expansion or alteration to the soil treatment area.
  • Minor Repair: Required for replacement of a septic tank.
  • Sealed Vault: Required for the new installation or repair of a sealed vault, vaulted privy, composting toilet, or vault and composting toilet. See guidelines for "Limited Use Wastewater Systems" for more information on these systems.
  • Remodel/Upgrade: Required for upgrades to the soil treatment area associated with building additions, basement finishes that increase the total number of bedrooms in a dwelling.
  • Site Evaluation: Required only if test pits must be inspected prior to a permit being applied for.

Application Process

  1. A soils test must be completed on the property prior to applying for the OWTS permit. The soils test will consist of either; percolation testing and two soil test pits, or two soil test pits dug in the area of the proposed soil treatment area. The soils test pits must remain open for inspection by Larimer County as part of the application process. To prevent accidents or injury, secure the opening of the test pit with fencing, stakes, or other appropriate measures. If test pits must be covered prior to applying for a permit a site evaluation may be requested, however a separate fee applies.
  2. Fill out an OWTS Permit Application and bring it in to either the Fort Collins, or Estes Park address listed above. A copy of the soils test report, design document, plot plan and engineer's design (if necessary) must be submitted with the application.
  3. Permit fees for each type of permit are listed at the top of the application form, payment is due at the time of application.
  4. For New System permits a soils report and sketch plan must be submitted with the application. The sketch plan contains basic calculations for the proposed system, and a plan of how the system will be installed. This may be included as part of the soils report, or for conventional, non-engineered systems provided separately. Under the following conditions the system must be designed by a professional engineer; Sites with a percolation rate that does not fall between 5 and 60 minutes per inch, or in soil types 0, 3A, 4, 4A, or 5. Areas where the depth to bedrock or seasonally high groundwater is 4 feet or less below existing grade. Systems utilizing pressure distribution. Sites where the proposed soil treatment area is on a slope of 30% or more.
  5. A plot plan must be submitted with the application for all permit types (example on opposite page). The plot plan may be hand drawn, but must identify property lines, existing structures, area of the proposed system, and approximate location of soils tests (percolation test and/or soil test pits).
  6. After applying for the permit, a site inspection will be made on the property by Department staff to determine the suitability of the site, inspect the test pits, and review soils report information. The site must be marked with the address, and soil test pits must remain open for inspection during the site inspection. To prevent accidents or injury, secure the opening of the test pit with fencing, stakes, or other appropriate measures. During winter months, site inspections and inspections of soil test pits may be delayed due to weather.
  7. If the application meets the Larimer County OWTS Regulations and the results of the site inspection are acceptable, a permit will be issued in approximately 5 days from the time the application was received. During the peak building season a longer turnaround may be expected.


  • Minimum system size for the tank and soil treatment area will be noted on the permit. It is important to read the permit prior to beginning construction for any details or additional inspections that may be specific to the project.
  • Requirements for a soils report may be waived for Major Repair permits in cases where previous testing information exists for the property, and a site inspection of a soil test pit indicates the depth to groundwater or bedrock is greater than 4 feet from existing grade.
  • System size is dependent on the number of bedrooms in the home, and the results of the soils test. In general, finer, clay type soils require a larger soil treatment area than coarser, sandier soils. If an unfinished basement or future addition may increase the number of bedrooms, it is recommended that the system be sized based on the future total number of bedrooms. The cost of adding to or upgrading a system that has already been completed can be significantly higher than adding additional capacity during original construction.

Sample Plot Plan

Provide a plot plan on a separate 8-1/2" x 11" sheet showing the following, the plot plan does not need to be to scale:

  • Location of the proposed OWTS;
  • Existing or proposed structures, wells (including neighbors), driveways, etc.;
  • Slope of property;
  • Location of soils test pits.

Septic Systems

Questions? Contact OWTS

(970) 498-6775