What a new septic system costs

The mound, aerobic and sand filter range is wide because the two cost guides that price these systems are far apart, so we give the range that covers both rather than a single band.

EPA lists the factors that change a system's design and size: household size, soil type, the slope of the site, lot size, how close it is to sensitive water bodies, the weather and local rules.¹⁰ Areas that don't suit a conventional system have rock close to the surface, very sticky clay, soil layers that hold water up, or shallow groundwater, NC State Extension says.¹¹

• Conventional. A septic tank and a drain field of trenches or a bed, typically installed at a single-family home.¹⁰
• Chamber. The drain field uses a series of connected chambers in place of gravel. EPA says it's easier to deliver and build, and suits areas with high groundwater or where gravel is scarce.¹⁰
• Drip. The drip lines go into the top 6 to 12 inches of soil, so no large mound is needed, but it needs a large dose tank after the septic tank and electrical power, which adds cost and upkeep.¹⁰
• Mound. An option where the soil is shallow, groundwater is high or bedrock is close to the surface. The tank's effluent goes to a pump chamber and is pumped in doses to a drain field built in a constructed sand mound.¹⁰
• Aerobic treatment unit. It adds oxygen to the treatment tank to boost the bacteria's work, and can serve smaller lots, poor soil, a high water table or a home near water sensitive to nutrients. EPA says to expect regular maintenance for the life of the unit.¹⁰
• Sand filter. The tank's effluent goes to a pump chamber and is pumped to the sand filter, often a PVC-lined or concrete box filled with sand, and is treated as it filters through, then goes to the drain field. EPA says sand filters cost more than a conventional system.¹⁰

A percolation (perc) test measures how long it takes water in a test hole to drop 1 inch. Soil that drains slowly needs a larger drain field, and soil that drains very slowly may not take one at all.¹² Under most programs the local permitting agency assesses the site to decide whether the soil can treat the wastewater.¹³ Your state's septic rules page says who does the soil evaluation where the state sets it.

In most states, local health departments issue the permits to install a septic system, under state law. You can apply yourself, or the contractor building the system can get the permit for you.¹³ Permit fees are set locally, so we don't give a national range for them.

• A septic tank on its own, without installing it. A tank's price isn't the price of a system.
• Connecting to city sewer instead. Connection fees are set by each sewer utility, so there's no national figure.
• Taking out an old tank. There's only one public estimate for it.

• Which kind of system the soil test and the permit allow, and why.
• Whether the price includes the soil test, the design, the permit and the tank.
• What upkeep the system needs, and whether the company offers a service contract for a system with a pump or an aerobic unit.
• How long the work will take once the permit is issued.

Each company on this site is listed with its phone number where it has one, so you can call two or three and compare. You can also use the request form to reach septic companies near you.