Conventional septic tank systems cost $3,500 to $8,500 to install the systems people are most familiar with. These conventional systems are primarily gravity fed and use anaerobic bacteria to break down solid waste in the tank.

The system consists of a septic tank, a drainfield, and 3 feet of native soil beneath the drainfield. A septic tank is a large, underground container that treats wastewater from rural homes that are not connected to a municipal sewer system. A drainfield, also called a leach field, is the area of land where the wastewater is dispersed and treated. The drainfield is made up of a series of perforated pipes buried in the ground and surrounded by gravel or sand which filter the wastewater.

A traditional septic tank system works by collecting waste in the septic tank, then letting gravity separate the waste into scum, sludge, and effluent.

• Scum is lightweight waste like grease, oil, and fats that float to the top.
• Sludge are heavy solids like bones and soil that settle on the tank's bottom.
• Effluent is the clear liquid wastewater left after the scum floats and the sludge settles.

Bacteria in the tank breaks down the solid waste on the bottom, while the effluent liquids travel out of the tank into the drainfield.

An alternative septic system is designed to deal with homesites with limited space or poor soil, when a drainfield is not a viable option. The most common alternative septic systems include:

• Chambered system – Uses a series of buried plastic chambers to treat wastewater.
• Constructed wetland system – Uses plants to absorb nutrients in the wastewater and help filter out the solids.
• Drip distribution system – Uses a series of drip emitters to evenly disperse the treated effluent wastewater from the septic tank to the leach field.
• Evapotranspiration system – Uses a drainfield lined with watertight material. As the effluent enters the drainfield, it evaporates into the air, never reaching the groundwater.

Choosing the right system depends on where you live, the condition of your soil, and your budget.

Septic tank maintenance is easy and inexpensive and comes down to these 4 essentials:

• Inspect and pump regularly – Schedule professional pumping services every 3 to 5 years.
• Use water efficiently – The less water you use, the less water enters the septic system. Reduce water usage by taking shorter showers and washing clothes only when you have a full load.
• Properly dispose of waste – Everything you flush down the toilet or pour down the sink eventually ends up in your septic system. Avoid flushing anything but toilet paper and don't pour chemicals or grease down the drain.
• Protect your drainfield – Do not park or drive over your drainfield to prevent damaging the system. Plant trees far away to keep roots from growing into the septic.

A concrete septic tank can last for 20 to 30 years with proper maintenance, depending on the tank material. Concrete tanks are the most expensive but the longest lasting tanks available. Other factors that can impact the lifespan of a septic tank include the quality of the tank, the soil conditions, and the usage.

Heavily used septic systems tend will likely need repairs or replacement sooner than rarely used systems. A septic tank in a household of 1 or 2 people will almost always last longer than one used by a large family.

Before you contract with a septic tank installer near you, ask these important questions:

• Is your company licensed, bonded, and insured for septic work?
• Are you a member of the National Onsite Wastewater Recycling Association (NOWRA)?
• How many years have you been installing septic systems?
• Does your estimate include permits, inspections, and site prep?
• What type of tank do you recommend for my property and soil conditions?
• What size tank do you recommend for my household?
• What guarantee do you offer on your labor?

HomeGuide has a great list of septic tank installers near you to choose from. When making your final list of installers to contact, don't forget to:

• Get estimates from 3 or more septic companies with years of septic system installation experience in your area.
• Select from septic companies that are members NOWRA.
• Check out the recent company reviews on HomeGuide and Google.
• Request everything in writing, including a detailed estimate, contract, and warranty information before starting the project.
• Confirm that the installer has the right permits and follows all local municipality laws and building codes.