Septic Systems (OWTS) (Health)

Septic Documents - Now Available Online

We have recently added the ability to locate and view septic documents on Larimer County's property records page. These documents can be viewed by searching for and selecting a property, and pulling up the 'Building Info' tab. If Larimer County has the septic documents on file, they will be linked there and can be viewed online.

Transfer of Title

2024 OWTS Application

2024 OWTS Application - Apply online.
This link will take you to our application portal for OWTS permits. Please note: first-time users will be asked to create an account.

A septic system or on-site wastewater treatment system (OWTS) is a self-contained, underground wastewater treatment system, most often used in rural areas.

The standard septic system involves a septic tank (to hold wastewater from drainpipes until solids settle out in the tank) and a system of pipes that distributes the remaining liquid waste underground over a large area — the leach field. The goal is to make sure that this filtration through the soil is sufficient to clean the wastewater before it reaches drinking water well sources or surface waters.

State and county laws require the Department to issue a permit before constructing or repairing a septic system.

Septic Fees

Permit Fees (Effective January 1, 2024)

New System: $1,540.00 + $20.00 CDPHE Surcharge = $1,560.00

Major Repair Permit: $1,130.00 + $20.00 CDPHE Surcharge = $1,150.00

Minor Repair Permit: $650.00 + $20.00 CDPHE Surcharge = $670.00

Limited Use Wastewater/Sealed Vault: $740.00

Commercial New & Repair: $2,250.00 + $20.00 CDPHE Surcharge = $2,270.00

Accessory Dwelling/Connection Inspection: $185.00

Self-Install: $300.00 in addition to new system, or repair fees above. Engineer-designed systems may not be self-installed by the property owner.

Site Evaluation Prior to Permit: $185 - only necessary if test pits must be back-filled prior to applying for a permit.

Septic Permit Instructions

Download the OWTS Permit Application Instructions as a PDF

Permit Types

New System: Required for all new construction and 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 or Upgrade: Required for upgrades to the soil treatment area associated with building additions, basement finishes that increase the total number of bedrooms in a home.
Site Evaluation: Required only if test pits must be inspected before a person applies for a permit.

Application Process

A soils test must be completed on the property before applying for the OWTS permit. The soils test will consist of either:
1. Percolation testing for leakages and two soil test pits, or
2. Two soil test pits dug in the area of the proposed soil treatment area.
  1. 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. A site evaluation may be requested if test pits must be covered before applying for a permit and a separate fee will be applied.
Fill out an OWTS Permit Application. You must include a copy of the following:
1. Soils test report
2. Design document
3. Plot plan
4. Engineer's design (if necessary).
You can submit your application and supporting documents online or bring them to the Department offices in Fort Collins, or Estes Park at the addresses listed at the bottom of this page.
Permit fees for each type of permit are listed at the top of the application form. Payment is due at the time of application.
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.
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).
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.
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.

Notes

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.

Site Evaluations for New Onsite Wastewater Treatment Systems

Site Evaluation Application This link will take you to our MyHD portal. Please note: first-time users will be prompted to create and account.

As of June 4, 2018 all applications for a new on-site wastewater treatment system must include an inspection of two test pits as part of the site and soil evaluation. Results of percolation tests may also be submitted, but must be done in conjunction with the evaluation of two test pits. The test pits must remain open for inspection by Larimer County, and can be inspected prior to permit application using this form.

A separate site evaluation and fee is only required if construction of the test pits will occur prior to applying for a permit, and the test pits must be backfilled immediately. Otherwise, the test pits may be secured by using fencing, staking a line around the perimeter, or other effective methods, and will be evaluated by Larimer County at the time of permit application. No additional fee for a site evaluation is required if test pits are left open for inspection after permit application.

After submitting an application for a site evaluation, arrangements will need to be made to schedule inspection of the test pits. Please allow a minimum of 5 business days for scheduling the inspection.

Soil test pits must be constructed per the following Site & Soil guidelines;

A minimum of two test pits in the area of the proposed soil treatment area. Generally, two pits set 40-50 feet apart in the proposed area is suitable.
The test pits must be dug to a depth of eight feet, or less if groundwater or bedrock is encountered before eight feet. The hole should be benched at a depth of four feet below grade and sloped back to the surface at 45 degrees to allow for entry to the benched portion.
The test pits must remain open for inspection by Larimer County and the soils engineer or system designer.

Find a Licensed Professional

Search for Licensed Septic Installers and Cleaners

Septic System Permit Records

Septic System Permit Record Request

This form can be used to request On-Site Wastewater Treatment System (Septic System) permit records. Results will be emailed to you. The physical address of the property and a parcel number provide the best results; however a search can be completed with one or the other. Any additional information; lot & filing, subdivision, owner or previous owner, etc. can be entered and may improve search results.

Not all properties have a permit, many properties built prior to 1973 do not have permit records available unless the system was repaired or upgraded after 1973. Records that appear on a “Non-Permitted Septic System” card provide information about the system obtained from an owner, cleaner, installer, but do not represent a permit issued by this Department.

Submissions to this web form are only monitored during normal business hours, Monday through Friday, 8 a.m. to 4:30 p.m. (excluding holidays). Please allow up to 3 business days to process your request.

General Construction Guidelines for New and Repair Installations

Guidelines for OWTS Installations

The following is a summary of frequently asked questions regarding construction requirements and code changes made during Larimer County’s adoption of Colorado’s Regulation 43 in June 2018.

Tank Lids and Access Risers
Access risers must be provided to grade on all tank lids, distribution boxes, and other components that require access for inspection or periodic maintenance. Lids must be watertight, and secured either with screws, bolts, chains or sufficient weight (>59 pounds).

System Dimensions

Standard, gravity style systems are limited to 12 feet wide and 100 feet long. If additional area is required, multiple beds may be installed with six feet of undisturbed soil between bed areas.
Systems may be installed no more than 48” below grade (to bottom of gravel or chambers). Permit details will specify if a shallower depth is necessary to provide adequate separation to bedrock or groundwater.

Distribution Boxes
If a distribution box (d-box) is used, flow equalizers must be installed on the outlet lines to adjust flow, and the d-box must have a watertight riser to grade for access.

Piping type, Bedding, and Clean-outs

Piping must be a minimum of SDR 35, no less than 4”, buried 12” below grade, with no less than 1/8” per foot (1%) fall for the building sewer to and effluent line from the septic tank. 1/4” per foot (2%) fall is recommended, and SCH 40 pipe (pressure rated) is required in pressure distribution systems and under driveways. Bell ends of gasketed pipe must be installed on the uphill side of the pipe section. Connections to the interior building sewer at the foundation must be made with glued fittings or flexible couplers with shear rings or shear guards.
Bends in piping are limited to 45 degree or sweeping 90’s, two 45 degree fittings are preferred and should be used to turn 90 degrees in the building sewer (house to tank). A cleanout is required within 5 feet of the building, for every 100’ of building sewer (line from house to tank), and wherever a bend of greater than 45 degrees is made, unless a cleanout is already located within 40’ upstream.
Piping must be bedded in material free of rocks or large clods prior to backfilling, use of sand or squeegee is recommended. The tank inlet and outlet must be backfilled and compacted to support the pipe prior to installation.

Trench Style Systems

When chambers are installed in trenches they must be installed in a single row, not to exceed 100’ for gravity systems (150’ for pressure dosed systems), with a minimum of 48” of undisturbed soil between rows, and an observation port at the end of each row. A reduction in the total number of chambers is given for trench style systems vs bed systems.

Construction Guidelines for Limited Use Wastewater

Limited use Wastewater

Download the Limited Use Wastewater Information as a PDF

Vault - A minimum 1250 gallon watertight, sealed tank designed to store wastewater. Vaults must be equipped with a signaling device to indicate when they are reaching capacity and must be pumped when full.

Vaulted Privy - A minimum 400 gallon concrete, plastic, or fiberglass tank with a "privy" or outhouse structure built over the tank.

Composting Toilet - A self-contained, waterless toilet unit that reduces waste through aerobic decomposition.

Portable Chemical Toilet - A temporary self contained privy and tank that are typically used during construction or to increase capacity for large temporary special events.

Graywater - Wastewater generated from lavatory sinks, showers, and laundry. Excludes wastewater from kitchen sinks and toilets.

What is a limited use wastewater system?
Limited use wastewater systems include vaults, vaulted privies, composting or incinerating toilets, and portable chemical toilets. These systems are intended to provide an option for handling wastewater on properties where the quantity of wastewater produced will be minimal, or properties which cannot accommodate an on-site wastewater treatment system (OWTS) with a soil treatment area.

Dwellings built as cabins without plumbing and hauling or hand carrying their primary source of water, RVs used on properties seasonally, and semi-permanent campsites are the primary users of limited use wastewater systems.

When can a limited use wastewater system be used?
Use of these systems is limited to seasonal or short-term use dwellings, properties that cannot accommodate an OWTS with a soil treatment area, areas where the installation of a full system is prohibited, or when the source of water is hauled or hand carried.

The cost of maintaining these systems can be very high due to the need for frequent pumping of vaults or holding tanks. Limited use wastewater systems are not permitted on properties that are used or could potentially be used for full-time occupancy, when water is provided by a well or public water supply, except in cases where a full OWTS is not feasible or prohibited.

Can a vault be installed for a cabin or seasonal dwelling?
A vault, vaulted privy, or composting toilet can be used provided the dwelling is built as a cabin per the Larimer County Land Use Code definition and Building Department requirements, and is built without plumbing or the source of water is hauled or hand carried to the site. Due to the high cost of maintaining these systems long-term, a full on-site wastewater system is recommended.

For structures built as a single family dwellings, cabins with water supplied by a well or public water system, or cabins converted to single family dwellings, a full OWTS must be installed unless the property cannot accommodate the full system with soil treatment area. Seasonal or part-time use alone can not be considered as a justification for a limited use wastewater system.

Can graywater be disposed of on the ground?
No, graywater from showers, laundry, or sinks must be collected and disposed of as wastewater. Running lines from RVs or dwellings out to the ground is prohibited by Larimer County OWTS Regulations.

Graywater contains bacteria, viruses, soaps and detergents, as well as other contaminants that can impact groundwater and surface water, potentially causing contamination to drinking water wells, lakes, and streams.

When is a permit required?
A permit is required prior to the installation of a limited use wastewater system. On new construction, arrangements must be made for how wastewater will be handled prior to a building permit being issued. On land that is currently vacant, a permit must be applied for prior to installing a vault or vaulted privy.

Limited use wastewater systems during construction
Portable chemical toilets are only permitted on properties during construction of a dwelling, or in emergency circumstances. Alternatively, a vault, septic tank used as a vault, or full septic system may be installed and connected to temporary living quarters until construction is complete.

Construction Guidelines for Pumps, Floats, and Controls

Download the Pumps, Floats, and Controls File as a PDF

Pressure Distribution to a Soil Treatment Area:

Designs for pressure distribution systems must include:

Pipe diameter for transport lines and laterals.
Orifice size and spacing.
A minimum 30 inch residual head for holes larger than 1/8” and 60 inch residual head for 1/8” holes.
Dose size and frequency.
Pump information, minimum gallons per minute and total dynamic head.

Piping for pressure distribution may be hung in the top of chambers or placed on the floor. Orifices must be directed upward if using chambers with drainage holes at either end of the lateral line or alternative spacing to allow piping to drain between doses.

If used with rock and pipe, the lateral piping must have at least 6" of gravel placed beneath the pipe and 2" above the pipe.

Cleanouts are required at the end of each line on a system using pressure distribution. Valves like the one pictured below, or threaded caps may be used.

Systems utilizing a pump to lift wastewater to a soil treatment area at a higher elevation or to provide pressure distribution must meet Section 43.9.I of the Larimer County On-Site Wastewater Treatment System Regulations. The following is a summary of the requirements:

High level alarm and pump control floats must be mounted to a separate stem from the pump outlet piping. This allows the pump to be removed and serviced without altering the float settings.
The discharge line must be protected from freezing through a weep hole placed on the outlet piping, directed down into the tank or drain back through the bottom of the pump. The piping must be sloped back to the tank or to the soil treatment area for drainage.
A quick disconnect or union must be installed on the pump discharge line and be within 18” of the access lid of the tank. This allows the pump to be removed without cutting the outlet line or hanging down inside the tank to make repairs.
All electrical connections must be made outside of the tank and riser. Run electrical connections for the pump and floats outside the riser to prevent corrosion. Leave enough extra wire to allow for removal of components.
For pressure distribution, the control panel must include a mechanism to track pump run time, and the number of pump cycles.
A switch must be included in the panel that allows for manual operation of the pump.
The control panel must include an audible and visual alarm and have a disconnect within line of sight of the pump chamber.

Additionally,

Control panels must be UL listed, and have the pump and high water alarm connected to separate control breakers.
The pump must be located in a screened vault, or an effluent screen provided in the chamber prior to the pump.

Construction Guidelines: Site and Soil Evaluation Requirements

The site and soil evaluation is an important part of the permitting process for on-site wastewater treatment systems (OWTS). The site evaluation is used to determine if site and soil conditions are suitable for installation of an OWTS, the size of the soil treatment area, and if any physical features such as lakes, creeks, irrigation ditches, drainages, or wells that may require setbacks to prevent possible contamination.

As of June 4, 2018 all applications for a new on-site wastewater treatment system must include an inspection of two test pits as part of the site and soil evaluation. All site and soil evaluations must be made by or under the supervision of a professional engineer.

Soil test pits must be constructed per the following guidelines;

The test pit(s) must be dug in the area of the proposed soil treatment area to a depth of eight feet, or less if groundwater or bedrock is encountered before eight feet. The hole should be benched at a depth of four feet below grade and sloped back to the surface at 45 degrees to allow for entry to the benched portion.
The test pit must remain open for inspection by Larimer County and the engineer or system designer. The test pit must be secured by using fencing, staking a line around the perimeter, or other effective methods. If the test pits must be backfilled prior to applying for the permit, a Site Evaluation may be requested, however a separate inspection fee is required.
If percolation testing will be completed on the site two test pits must also be evaluated.
Results of the test pit evaluation and percolation test (if completed) must be submitted with the OWTS application.

A soils report is required for all systems. The report must show calculations for each component, a proposed layout of the soil treatment area, depth of tank, proposed dimensions of trenches or beds, distribution boxes, manifold, or other components. For standard systems the may be included as part of the soils report, or submitted separately. If any of the following conditions exist 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 R, 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.

Percolation tests are not required if two soil test pits are evaluated by the engineer or system designer. If percolation tests are performed they must follow the guidelines in the regulations. Two test pits must be dug regardless of whether percolation testing is performed or not.

Minimum of three test holes, 8-12" in diameter, spaced in area where soil treatment area is to be located.
Depth of holes must be 6-18" below proposed infiltrative surface. If unknown, holes of varying depths may be used, maximum percolation test depth is 5- 1/2 feet below existing grade.
Add 2" sand or gravel to bottom of hole, presoak hole 24 hours prior to conducting test.
Adjust water depth to 6" above sand or gravel in bottom of hole, measure the water level drop over 30-minute intervals for 4 hours. Refill water level to as necessary throughout test.
The water level drop in the final 30-minute interval is used to calculate the percolation rate, NOT an average of all drops recorded for the hole.
The duration of the test may be reduced to 2 hours if by that time 3 successive water level drops have stabilized.
Sandy soils where all the water (after the presoaking period) seeps out within 30 minutes may take measurements every 10 minutes for a period of 1 hour.

A one foot width by three foot length trench in the ground.

On-Site Wastewater Treatment System Regulations

2024 Larimer County Onsite Wastewater Treatment Systems Regulations

Septic Systems

Questions? Call OWTS at (970)498-6775

Search for Septic Documents by property address
On the property details page, under the Building Info tab and Property Attributes & Descriptions heading (Attribute: Sewer)

Septic Systems (OWTS)