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Septic system requirements in Colorado

What landplan.io applies when it designs a septic system in Colorado: the system types allowed, tank sizes, setbacks and soil loading rates, with what septic products cost there.

Updated

Design a septic system for an address in Colorado

Reviewed landplan.io designs by Colorado's own rules, which our staff reviewed against the state's regulations. Last published 16 October 2026.

8system types permitted
1,000 gallonssmallest septic tank
31septic companies located here
50 of 64counties with parcel data

Septic systems allowed in Colorado

The system types landplan.io permits in Colorado:

Septic tank size in Colorado

The daily design flow of a home: 150 gal/day per bedroom, at least 300 gal/day. The septic tank is sized from that flow:

Septic Tank: minimum size by daily design flow
Daily design flowMinimum tank
up to 450 gal/day1,000 gallons
450 to 600 gal/day1,250 gallons
600 to 750 gal/day1,500 gallons
750 to 900 gal/day1,750 gallons
900 to 1,050 gal/day2,000 gallons
1,050 to 1,200 gal/day2,250 gallons
1,200 to 1,350 gal/day2,500 gallons
1,350 to 1,500 gal/day2,750 gallons
1,500 to 1,650 gal/day3,000 gallons
1,650 to 1,800 gal/day3,250 gallons
1,800 to 1,950 gal/day3,500 gallons
1,950 to 2,100 gal/day3,650 gallons

Septic setbacks in Colorado

Minimum distances
FromToDistance
LineStringCut Bank10 ft
LineStringDry Gulch10 ft
LineStringFill Area (from Crest)10 ft
LineStringIntermittent Agricultural Irrigation Lateral10 ft
LineStringIrrigation Channel50 ft
LineStringIrrigation Ditch10 ft
LineStringPotable Water Supply Line50 ft
LineStringStream50 ft
LineStringSubsurface Drain10 ft
LineStringUpslope Curtain Drain10 ft
LineStringWatercourse50 ft
PointDrywell10 ft
PointSpring or Well, Suction Line, Underground Potable Water Supply Cistern50 ft
PolygonExisting Septic Component to be Abandoned5 ft
PolygonLake50 ft
PolygonStructure w/basement, crawl space or footing drains5 ft
PolygonStructure without basement, crawl space or footing drains5 ft
PolygonUtility Easement10 ft
PolygonWetland50 ft

Soil loading rates in Colorado

The range over the soil groups of each table
TableLowestHighestSoil groups
Soil Loading Rate0.1 gal/day/ft²0.8 gal/day/ft²8

landplan.io picks the rate from the soil test: texture, structure and percolation.

These are the values the landplan.io design engine applies in Colorado. Confirm a design with the Colorado health department or your county's before you build.

Parcel data in Colorado

landplan.io has parcel boundaries for 50 of Colorado's 64 counties, and part of 6 more: the counties where 97.8% of the state's people live. Type an address there and the design starts from the parcel.

Septic companies, designers and jobs in Colorado

Where the rules come from

The regulations and documents landplan.io's Colorado rules are read from:

Septic rules by county in Colorado

Questions

What septic systems are allowed in Colorado?

landplan.io permits these system types in Colorado: Mound System, Non-Pressurized Drip Dispersal Systems (NDDS), Leaching Trench System, In-Ground Bed, In-Ground Bed Pressure Distribution, Drip Distribution System, Infiltrator Advanced Enviro-Septic® (AES) and Discharging System.

What size septic tank do I need in Colorado?

landplan.io sizes the septic tank in Colorado from the daily design flow: up to 450 gal/day: 1,000 gallons; 450 to 600 gal/day: 1,250 gallons; 600 to 750 gal/day: 1,500 gallons; larger flows need larger tanks. A home's design flow is 150 gal/day per bedroom, at least 300 gal/day.

How far must a septic system be from a well in Colorado?

landplan.io keeps these distances in Colorado: Point to spring or well, suction line, underground potable water supply cistern: 50 ft; Point to drywell: 10 ft.

Does landplan.io have parcel data in Colorado?

Yes, for 50 of Colorado's 64 counties, and part of 6 more.