Above Ground Septic System (Mound Systems): How They Work & When You Need One

October 3, 2025

Sometimes, a standard septic system isn’t the right solution. An above ground septic system, also known as a mound septic system or sand mound septic system, is designed for properties with poor soil, high groundwater, or shallow bedrock. This setup provides safe and efficient wastewater treatment when traditional options fail. In this guide, we’ll explain how a mound septic system works and when installing a septic tank mound system is the best choice for your home

What Is an Above Ground Septic System?

An above ground septic system, often called a sand mound septic system or septic tank mound system, is a wastewater solution designed for challenging sites. Homeowners typically choose this setup when soil doesn’t drain well, groundwater is high, or bedrock is too close to the surface.

This system has three main parts:

Septic tank – Collects wastewater and separates solids.
Pump or dosing chamber – Moves effluent evenly into the mound.
Raised sand mound – A layer of sand and gravel where wastewater is filtered and treated before entering the soil.

By adding this elevated treatment area, a mound septic system ensures wastewater is safely processed, even when traditional systems won’t work.

How Does a Mound Septic System Work?

An above ground septic system, also known as a mound septic system, uses elevation and sand filtration to treat wastewater safely. This design ensures proper treatment where traditional septic drain fields cannot work.

Main Components

Septic tank – The first stage of an above ground septic system, where solids settle and scum is removed.
Pump/dosing chamber – Moves effluent from the tank into the mound in controlled doses.
Mound (sand/soil bed) – A raised bed of sand, gravel, and soil where wastewater is naturally filtered before reaching the ground.

Treatment Process

Wastewater leaves your home and enters the septic tank for primary treatment. From there, the pump chamber sends effluent into the septic tank mound system. Inside the raised sand mound, water trickles through layers of gravel and sand. Here, natural bacteria break down contaminants, producing cleaner effluent that seeps safely into the soil.

This step-by-step process makes a sand mound septic system a reliable solution for properties with poor soil, high groundwater, or shallow bedrock.

Above Ground Septic System (Mound Systems): How They Work & When You Need One

When to Use an Above Ground Septic (Mound) System

An above ground septic system, or mound septic system, is the go-to solution when traditional drain fields fail. These systems protect groundwater and ensure safe wastewater treatment in challenging soil conditions.

This system is ideal when:

Soil is too shallow, clay-heavy, or drains too quickly. A sand mound septic system ensures proper filtration where natural soil can’t.
The water table is high or bedrock is close. An above ground septic system keeps wastewater elevated, reducing contamination risks.
Groundwater protection is critical. Homes near lakes, rivers, or sensitive environments benefit from a septic tank mound system.

By using a raised bed of sand and gravel, the mound septic system provides safe, effective treatment where underground systems aren’t possible.

Pros & Cons of Sand Mound Septic Systems

A sand mound septic system, also called an above ground septic system, has unique strengths and challenges. Understanding both helps homeowners decide if it’s the right fit.

Benefits

Makes difficult sites usable. A mound septic system allows safe wastewater treatment on properties with poor soil or high groundwater.
Uses natural soil layers. The septic tank mound system filters effluent through sand and soil for cleaner water.
Protects water quality. A sand mound septic system reduces the risk of surface or groundwater contamination.

Drawbacks

Higher upfront cost. Installing an above ground septic system is more expensive than a conventional drain field.
Needs expert installation. A septic mound system must be carefully designed and maintained to prevent failure.
May affect landscaping. The mound can stand out in a yard unless blended with shrubs or cover plants.

Maintenance Tips for Mound Systems

Keeping your above ground septic system in good shape protects your home and investment. Regular care helps prevent costly breakdowns.

Pump regularly. Inspect and pump the septic tank and dosing chamber every 1–3 years.
Conserve water. Using water wisely avoids overloading your mound septic system. Spread out laundry and limit heavy daily use.
Protect the mound. Keep vehicles, heavy equipment, and deep-rooted plants away from your sand mound septic system.
Watch for warning signs. Soggy areas, foul odors, or alarm alerts may indicate issues. Call a licensed pro immediately.

Conclusion

An Above Ground Septic System (mound system) is a smart solution for homes where soil or groundwater challenges make traditional septic systems impossible. By combining a septic tank mound system with sand and soil filtration, it provides reliable wastewater treatment and protects groundwater.

If you’re dealing with shallow soils, high water tables, or sensitive environments, a sand mound septic system may be exactly what your property needs.

Trust the experts to design, install, and maintain your above ground septic system—ensuring safety, compliance, and long-term peace of mind.

Need help deciding if a mound system suits your property?

Contact Advanced Septic Services at 780-691-0588 or visit advancedsepticservices.ca for expert guidance and design that fits your site’s needs.

FAQs

1. What are the pros and cons of above ground septic systems?

Pros:

Work in areas with shallow soil or high groundwater.
Reduce risk of groundwater contamination.
Offer reliable treatment when conventional systems fail.

Cons:

More expensive to install.
Require frequent maintenance.
Mound may not blend with landscaping.

2. What is a Type 3 septic system?

A Type 3 septic system uses advanced treatment methods, like aeration or disinfection, to produce higher-quality effluent. It’s often required in environmentally sensitive areas where groundwater protection is critical.

3. What is an elevated septic system?

An elevated septic system is another term for a mound septic system. Instead of placing drain fields underground, effluent is pumped into a raised sand and gravel mound for treatment.

4. Why is my septic tank above ground?

A septic tank may appear above ground when the property has shallow bedrock, high groundwater, or poor soil. Raising the tank and mound helps wastewater filter safely without contaminating nearby water

5. Which type of septic system is best?

The best septic system depends on site conditions. For standard soil, a conventional system is cost-effective. For poor soil or high water tables, an above ground septic system (mound system) is the safest choice.

6. How does an above ground septic system work?

Wastewater flows from the house into a septic tank, where solids settle. Then, effluent is pumped into a sand mound septic system, filtering through sand and gravel before safely reaching groundwater.

7. What is the difference between above ground and below ground septic tanks?

Above ground septic systems use a raised mound of sand and gravel for filtration.
Below ground systems rely on natural soil absorption.
The choice depends on soil quality, groundwater levels, and site restrictions.

8. What is the most expensive part of a septic system?

The drain field (or mound system) is usually the most expensive part. It requires engineered design, large amounts of sand/gravel, and careful installation to ensure long-term performance.