A septic system is an on-site wastewater treatment system used for managing the waste generated by a home or business. Sewage lines carry wastewater from your shower, toilet, sinks, clothes washer and garbage disposal out of the house and into a septic tank buried in the yard. In the septic tank, the heavier solids separate from the floatable matter and the remaining liquid drains out from the tank through a series of perforated tubes into a drain field or leach field. As the liquid filters down through the soil, dangerous bacteria is removed, making the water safe once more.
Septic systems are commonly used in rural areas without a centralized city sewer system. Septic systems can be installed during new construction of a home or building, or they can be replaced by removing an existing tank and installing a new one. Tank capacity ranges from under 1,000 gallons to 2,000 gallons or more. Homeowners can either provide the materials for a new septic system themselves or ask a septic system professional to provide them. Septic system installation or replacement is available for condos, apartments, homes, commercial spaces and other buildings. The costs for installing or replacing a septic system depend on several factors.
The accessibility of the current septic tank or the site of the new system affects the cost of installation. For example, if the proposed site is under a concrete driveway, that driveway may need to be demolished and removed, which will add to overall costs. If there is a large tree with an extensive root system that has to be navigated, costs will also increase.
Tank size and type
Residential septic tanks typically range in size from 800 to 1,300 gallons. According to Milan and Son Plumbing in Deerfield Beach, Florida, this size is good for an average two- to four-bedroom home. The price of septic tanks increases as the holding capacity increases. Septic tanks continually self-clean, so getting a bigger tank doesn’t mean homeowners can avoid maintenance for longer. A two-bedroom house is fine with an 800-gallon tank because the household has less wastewater to process on daily basis than a four-bedroom home, which might need a 1,200- or 1,300-gallon tank. Plastic tanks are less expensive than concrete tanks and are easier to move and install, but these are not authorized for use in all states and can sometimes rise to the surface if not properly installed. Here are some examples of the cost of septic tanks:
Plastic septic tank, ranging in size from 750 gallons to 1,500 gallons: $500–$1,500
- Concrete septic tanks ranging from 750 gallons to 3,000 gallons: $1,300–$5,000
In addition to expert knowledge of code and installation techniques, plumbing companies that install septic systems need heavy machinery when working with concrete tanks. Milan and Son Plumbing has a backhoe tractor that crews use to prepare the earth and dig the hole at the installation site. An average concrete septic tank can weigh 8,000–12,000 pounds, depending on gallon capacity. Milan and Son Plumbing secures the tank to the backhoe, carries it to the install site and lowers it into the ground. According to Milan and Son Plumbing, there are many variables to a proper installation. The ground at the base has to be level, and if the tank is not installed correctly the first time, it must be repositioned. If it rains during installation, the wet ground can pop a tank out of place and it will have to be redone. Installation costs often depend on the business and operating costs of owning an $80,000 backhoe tractor.
Installing a new system or replacing an existing system can take two to five days—usually three days on a typical job. Wet weather, extenuating soil circumstances (such as tree roots) or site inaccessibility can extend the installation by a few days. Prices for installation vary depending on the type of the septic tank (concrete or plastic), the size of the tank, the cost of labor in the region and any additional prep work that must be done to prepare the ground for installation. Milan and Son Plumbing charges, on average, approximately $9,000 to remove an old tank and install a new system. Some jobs have cost as much as $12,000 because of difficulties at the property site and tree roots.
The EPA recommends that property owners have their septic tank pumped every three to five years. A licensed plumber can pump out the tank without having to remove it from the ground. According to the EPA, "If the bottom of the scum layer is within six inches of the bottom of the [tank] outlet or if the top of the sludge layer is within 12 inches of the outlet, your tank needs to be pumped." Milan and Son Plumbing charges $300–$500 to pump a septic tank.
In some cases, the house or septic tank is lower than the drain field and a lift station is required. A lift station is a type of pump that kicks on when the waste in the tank reaches a set level. This mechanism ensures that wastewater continues to flow out of the tank and into the drain field, keeping the operating system working properly—regardless of gravity. "We see the need for more of these in the Miami area, where the homes are lower in elevation than their backyards," say the experts at Milan and Son Plumbing. The company charges an additional $3,000–$5,000 to install a lift station.
Alternative septic systems
For steep sites, extremely rocky ground or bad soil, alternative systems work well. These include aerobic septic systems, mound septic systems, raised-bed septic systems and others. Depending on the location and type of system, costs may be higher or lower than the average septic system installation or replacement.