Highlights
Septic systems cost an average of $6,400 to install.
Sewer systems cost about $3,200 to install.
You won't pay utility bills for septic systems, but maintenance costs are often higher.
Not all areas have access to a sewer, making septic system a great option.
Septic tank versus sewer system? We know there's nothing pleasant about wastewater. But if you're about to move into a new home or build one from scratch, knowing the difference between a septic tank and sewer system is crucial. Septic and sewer systems have the same job—to treat wastewater and keep harmful bacteria and chemicals from entering our water supply. We'll walk you through how sewer systems and septic tanks work and which one is best for your home.
Septic System Pros and Cons
Let's kick things off by explaining how a septic system works. A septic system treats all wastewater that comes from your home—from the dishwasher to the toilet—on site. Waste flows out of your home through a main line and into a water-tight septic tank through an inlet pipe.
Once inside the tank, the waste separates into several layers. And just a heads up, the layers do not have lovely names. Solids known as sludge—we warned you—fall to the bottom of the tank while grease and oil, known as scum, form a layer that floats on the top.
The remaining water in the middle—called effluent—passes the test to move on to the next treatment area through an outlet pipe and into a drain field. A drain field, or "leach field," includes unsaturated soil, pipes, and chambers that treat the water further. Oxygen, microbes, and bacteria in the soil remove the final harmful materials in the effluent before it heads back into the earth.
As you can imagine, building and maintaining such a complex system in your backyard can be complicated. When well-cared for, however, septic systems can be both cost-effective and highly beneficial for rural areas.
Pros
Ideal for rural areas without access to city sewer systems
No monthly costs outside of maintenance
Naturally treats water
If there are leaks, contamination is concentrated to one area
Easier to install compared to new city line hookup
Cons
Requires pumping every three to five years
Replacement is more expensive than sewer
Solid materials are more likely to clog and back up systems
Leaks can lead to potent and unhealthy waste in your backyard
Roots can damage septic system pipes
Sewer System Pros and Cons
If you live in a town with a sewer system, a main pipe will carry all wastewater away from your home and connect to a city-wide network of pipes. These pipes transport all waste to a nearby treatment plant.
In a home sewer system, all of your pipes empty to what's known as the sewer lateral—basically, the large pipe that sends wastewater to the city's main line. The sewer lateral breaks into two parts—the upper and the lower lateral. The upper sewer lateral runs underneath your yard and while the lower lateral typically extends into the city street to the main line.
Along your main line, you'll also have two main cleanout pipes. These include the main cleanout close to your home and a property line cleanout at the property line.
Pros
Easy access to clogged pipes
Sewer systems can handle heavy rains or excess water
Main sewer line repairs are the responsibility of the city
Lower installation and maintenance costs
Cons
Pay an annual fee to the city for sewer system use
Main sewer lines can crack, breakdown, or become clogged
Roots impede on sewer laterals over time
Connecting a new home to a city's system can be complicated
Septic System vs. Sewer System
If you're moving to a rural area in the mountains or a remote area by the sea, you may simply not have access to a sewer system. However, some areas are slowly extending sewer systems to homes that previously didn't have access, giving you the option to convert. If you're on the fence, here are the two systems side by side in several scenarios.
Installation Cost
Sewer system hookup costs less than installing a new septic system, but both cost a pretty penny. Between digging a trench, laying pipe, and city permits to connect to the city main line, the cost to install a sewer line averages $3,200. Septic system installation costs nearly double, at $6,400, but this number varies depending on permits, regulations, and labor rates where you live.
Ongoing Costs
Every three to five years, it's important to have your septic system pumped and checked for any necessary repairs. On average, pumping a septic system costs $0.30 a gallon or around $400 as a flat fee. The cost of septic repairs, on the other hand, ranges anywhere from $200 for a new filter to $1,500 for main line replacement.
However, your sewer line utility bill will cost you anywhere from $14 to $135 a month, depending on where you live in the country. If you live in an area on the higher end, a septic system will quickly pay for itself compared to a sewer line.
On the other hand, sewer line repairs are less common, unless the system is over 50 years old and requires updates. When they are needed, the cost of sewer line repairs is an average of $1,700 but basic inspections and cleanings range between $200 and $500.
Ease of Maintenance
Stay on top of your sewer line maintenance by calling a local plumber every 18 to 22 months. They will perform a basic inspection and clean your main line to break down any developing clogs.
As we mentioned earlier, it's only necessary to pump your septic system every three to five years, but the process is a bit more extensive than checking your sewer line, especially as the system gets older.
For example, sewer systems only have one main line that carries water away from your home, whereas septic systems depend on the pipes, tank, and leach field to all hold up over the years.
Longevity
A main sewer line can last between 50 to 100 years depending on its material, age, and proximity to invasive tree roots in your yard. Earthquakes can also shorten this lifespan.
One of the myths about septic systems is that you never need to replace them. In reality, septic systems last an average of 20 to 30 years, meaning you could end up replacing all or part of the system much quicker than a sewer line.
The Verdict
Septic or sewer? All in all, a septic system costs more and requires more ongoing maintenance over time, but a sewer system comes with monthly utility bills. The right option for you will likely come down to where you live, the layout of your property, and your city's recommendations. Get to know your local plumber if you've just moved to town or started the home construction process.
