Plan ahead! Both the Castle Rock and Lone Tree Health Department offices will be closed on Tuesday, Nov. 19 from 11:45 a.m. – 1:45 p.m.
Plan ahead! Both the Castle Rock and Lone Tree Health Department offices will be closed on Tuesday, Nov. 19 from 11:45 a.m. – 1:45 p.m.
An On-site Wastewater Treatment System (OWTS) permit is required for new installations, expansions, and repairs (with some exceptions). To obtain a permit, the following will be required for new systems/new soil treatment areas (STA’s):
Environmental Health staff will then review the information and make a site visit. If the application, design (if applicable), and site meet our requirements, we will issue a permit to construct, expand or repair the OWTS.
A Colorado Licensed Professional Engineer must design a system if any of the following occur:
Review our Use Permit FAQs and visit our On-Site Waste Treatment System page for more information and related forms.
Use permit inspections must be completed by a third-party Use Permit Inspector, certified by the National Association of Wastewater Technicians (NAWT). These types of inspectors do not work for Douglas County.
The seller of the property is required to obtain a use permit prior to the sale of the property. For more information visit our Use Permit FAQs.
Douglas County does not have a minimum lot size requirement. Local planning agencies do have minimum lot sizes in their zoning codes. They typically recommend a minimum of one acre for lots supplied by central water and 2.5 acres for lots with wells.
The Douglas County Health Department requires septic tanks to be inspected every four years and pumped when scum and sludge accumulate to greater than 25% of the effective volume of the tank. Dosing tanks shall be inspected and pumped if sludge accumulation is observed.
If your OWTS receives higher than average use as determined by your licensed cleaner, you may want to consider a more frequent pumping interval. All pumping and evaluation of septic tanks should be done by a licensed cleaner. For more information, please visit our Septic System Education and Care page.
We recommend that an STA be left largely untouched by homeowners. Horses or other livestock should not be placed on an STA because compaction of the soils may occur causing premature failure of your absorption area. Irrigated landscaping is not recommended, since it has the possibility to saturate an STA, causing the septic system to fail prematurely. You may consider planting buffalo grass or other natural grasses which do not require irrigation. Mow any grasses planted on the STA area regularly.
We generally allow the connection of bathrooms in buildings that are not dwellings to the existing septic system, provided the owner notifies the Douglas County Health Department in advance and the connection is approved. An inspection of the new plumbing and payment of applicable fee(s) are required. Prior to final approval, the existing recorded drawing of the system must also be amended to show new buildings and plumbing. For more information, contact our Environmental Health office prior to starting your project.
Locate septic permit records using the OWTS Permit Map where you can also search by address or owner name. In some instances, Douglas County may not have received historical permits from the Tri-County Health Department. If a record is not found, please contact Douglas County Environmental Health at 720-906-4886 or email EH@douglas.co.us. It may be necessary to contact a licensed installer or a certified Use Permit inspector or surveyor to locate your system.
If an OWTS is damaged, it is best to have the system evaluated by a licensed septic contractor. If the damage is relatively minor, such as damage to a single pipe or chamber, it likely will not require a permit, but the repair will need to be completed by a licensed contractor. All repairs will need to be inspected by DCHD prior to being covered. Inspection fees may apply. If the damage is more extensive, such as damage to the tank or extensive damage to the soil treatment area (STA), it may require a repair permit. Please consult with your contractor and Douglas County Health Department Environmental Health staff.
