Choosing the right septic system for your home means making sure your household is properly supported for the long term. In addition to the size of your home and your water usage, varying factors like your soil type, lot size, and groundwater levels all must be taken into consideration—which means a standard system doesn’t always cut it.
As a septic system installer in Northern Colorado, we specialize in both standard and engineered systems to meet these needs. Whether you’re determining the size of your tank for a septic replacement or designing a more customized solution due to limited space, we provide expert guidance on choosing the right system for reliable, long-lasting performance.
In this blog, we’ll cover how to determine what size septic system your home needs, when an engineered system might be required, and what to expect from the design and installation process so you can make the right choice for your property.
- What Size Septic Tank Do I Need?
- Types of Septic Systems
- Considering Factors Unique to Your Region
- Engineered Septic Systems
- The Installation Process
What Size Septic Tank Do I Need?
How to Size a Septic System
When sizing a new septic system for a new build or a home addition, the first thing to consider is how many people your home serves. Most residential systems are based on the number of bedrooms, which helps estimate daily water use. In general, a three-bedroom home needs a 1,000-gallon tank, while larger homes may need 1,250 gallons or more.
Note that the number of bedrooms in your home is just a guideline for estimating septic size. Homes with large households or high water use from hot tubs, laundry, or garbage disposals may need a larger tank or advanced treatment. In addition to your water usage, local regulations, soil type, and future plans for your property all will play a role in choosing the right system.
Why does it matter?
Your septic tank’s capacity must match not only your household demand but also the soil absorption and drain field performance. Undersizing a system can cause backups, while oversizing causes wastewater to sit too long, allowing solids to settle before bacteria can break them down—often leading to odor problems and buildup that reduces septic system performance over time.
Properly sizing your system directly affects its lifespan, its efficiency, and groundwater safety. With Colorado’s variable terrain and groundwater levels, the right sizing and system type will protect your investment, your home, and your local environment.
Types of Septic Systems
Septic systems can vary throughout Colorado depending on the soil and percolation rate on your property, the slope of your lot, and your lot size. Some of the most common systems include:
Conventional, Gravity-Fed Septic Systems
Traditional gravity-fed systems are best for large lots with deep, permeable soils. In a conventional septic system, waste flows naturally from the tank to the drain field without pumps or pressure systems. These systems are affordable and low-maintenance, but unsuitable for shallow or rocky soils.
Ideal for Weld County’s sandy soils or other areas with deep, permeable soils. Less common in Boulder or Jefferson mountain areas where soils are shallow or rocky.
Pressure Distribution Systems
Pressure distribution systems use a pump to move effluent from the septic tank evenly across the drain field through a network of small-diameter pipes. This prevents overloading any single area of the drain field and allows wastewater to be applied in measured doses.
Ideal for sloped lots, shallow soils, or irregular terrains, where gravity alone won’t spread effluent evenly—such as foothill areas in Larimer County or Jefferson County. Also useful near rivers to avoid localized saturation.
Mound Systems
Mound systems elevate the drain field on a constructed sand mound when soil conditions or groundwater levels are inadequate. Effluent is pumped from the tank into the mound, where it filters through the sand before reaching the native soil.
Ideal for areas with shallow bedrock, high water tables, or compacted clay, such as Boulder County foothills, Jefferson County slopes, and parts of Larimer County.
Aerobic Treatment Units (ATUs)
An ATU adds oxygen to the wastewater, speeding up bacterial decomposition before effluent is released into the soil. This advanced treatment allows for smaller or more constrained drain fields and reduces environmental risks.
Ideal for tight lots, high groundwater areas, or sites near sensitive watersheds like Boulder Creek or the St. Vrain River and can be used in any of the Northern Colorado counties when conventional systems won’t meet code.
Knowing Your Ground: Region-Specific Considerations in Colorado
Soil, slope, and water conditions shift from one area to the next along the Colorado Front Range. Knowing what’s typical in your area can help you choose the right system for your property.
Weld County
Weld County has clay-heavy soils in the west and sandy ground toward the east. Seasonal groundwater near the South Platte River can complicate drainage, especially in flood-prone zones. These conditions often require chamber systems in clay areas or mound and aerobic systems where water tables rise seasonally. The Weld County Health Department mandates at least two soil test pits, engineered designs for challenging sites, and new inspections when adding bedrooms or upgrading older systems.
Larimer County
From the plains around Fort Collins to the rocky slopes near Estes Park, Larimer County has a mix of soil and elevation challenges. Shallow bedrock in the foothills limits drain field depth, while higher water tables along the Poudre and Big Thompson Rivers require extra consideration to prevent contamination. Pressure-dose and mound systems are common solutions here. The county requires two test pits per site, groundwater monitoring data, and documented septic pumping every three to four years to maintain compliance.
Boulder County
Boulder County’s terrain ranges from rocky foothills to flatter agricultural land near Longmont. Many mountain properties sit on thin soils over bedrock with steep grades and protected watersheds. In these cases, advanced treatment options like sand filters or Aerobic Treatment Units (ATUs) are used to meet environmental standards. Boulder County Public Health enforces strict setbacks from water sources and requires engineered soil reports with professional certification for all new or replacement systems.
Jefferson County
Covering everything from mountain properties in Evergreen and Conifer to foothill suburbs, Jefferson County has shallow soils, fractured rock, and freeze-thaw cycles. Homeowners here often need mound or pressure distribution systems. New builds must go through Site Development Review, and operating permits include annual maintenance logs and strict setbacks from wells and streams to protect water quality.
Need a custom septic solution? Reach out to us for an estimate, site visit, or consultation today.
Engineered Septic Systems: Perfect for Tight Lots, Complex Layouts, or Challenging Soils
Not every property in Northern Colorado can support a standard septic design. That is why we specialize in engineered septic systems as a solution for sites with limited space, steep slopes, high groundwater, or complex drainage. By designing a custom solution around your property’s exact soil, slope, and usage needs, an engineered system maintains reliability and compliance where conventional options would fail. They’re also ideal for additions, rebuilds, and properties near protected watersheds that require enhanced treatment.
Site Specific Solutions for Long-Lasting Results
As a septic system installer in the Colorado Front Range, we engineer solutions, not generic installs. As part of our installation process, we offer:
- Free site evaluations
- All permitting included
- Soil testing and perc reports
- Designs tailored to slopes, rock, or high water tables
- Full installation and startup
Septic System Design & Installation with Ace Septic & Excavation
Have peace of mind knowing that your septic system is designed and built to last. With a septic solution unique to your property’s needs, you can minimize the costly issues that come with outdated or poorly performing systems.
Get a personalized site inspection for your new septic system today!
Ace Septic & Excavation is a septic contractor in Loveland, Colorado, serving the surrounding Weld, Larimer, Boulder, and Jefferson Counties. Specializing in both residential and commercial systems, we install traditional septic systems as well as engineered solutions for your property or business.