What Is a Septic Tank and How Does It Work?
This part of your system may stink, but it’s very important
Highlights
A septic tank is one (important) component of a septic system, which is a waste treatment option for homes that aren’t connected to a city sewer system.
Septic tanks are made of concrete, fiberglass, and plastic and must be installed at least 5 feet away from your home.
Septic tanks use natural processes to separate solid waste, oil, and grease from wastewater in conjunction with a drain field.
Septic tanks must be pumped, or emptied of sludge, once every three to five years.
When properly maintained, a septic tank can last up to 30 years.
Ah, the magic of indoor plumbing: You do your business, flush, and voila! That’s the end of the story. Unless, of course, your home isn’t connected to a city sewer system. In that case, you’re responsible for finding your waste’s final resting place—and one of the best ways to take care of that problem is a septic system. But what is a septic system exactly, and how does it work?
In a septic system, a septic tank and a drain field work together to safely remove and digest solid waste from your home’s wastewater. The system relies on natural processes to do so, and if installed correctly and maintained properly, it can work in a very cost-effective way.
But it all starts with the septic tank itself, which can be added to your property by a professional septic tank installer near you. So let’s take a closer look at what a septic tank is and what it’s used for.
What Is a Septic Tank?
A septic tank, as its name implies, is a watertight tank that’s used to aid in the process of treating wastewater. The tank is usually buried underground at least 5 feet away from your home, but usually further; in most cases, the tank will be buried 10 feet from the house, and the drain field will be even further away. (One caveat: Above-ground septic tanks do also exist.)
Septic tanks can be made of concrete, which is the most expensive option, as well as fiberglass and polyethylene (plastic). Septic tanks may be round or rectangular in shape. They do require certain maintenance efforts and expenses, but when installed correctly, a septic tank can be a low-cost form of waste management.
How Does a Septic Tank Work?
When you use the sink, shower, or toilet, the septic tank is the first stop on the wastewater’s journey. Its purpose is to begin the process of digesting and eliminating waste.
A septic tank uses natural processes, including the impact of beneficial bacteria, to separate solid waste and scum from the wastewater that comes from your home. As wastewater builds up, a correctly working septic tank separates it into three layers:
Scum floats on top of the wastewater and is composed of oil, fat, and grease, which can come out in your wastewater when you wash dishes (or your hair, for that matter). These components naturally float to the surface of the water over time.
Effluent, which is the middle (and cleanest) layer of the wastewater, is left over after scum and sludge both separate from it.
Sludge, the bottom layer of waste, which includes solid human waste as well as other denser waste products that sink to the bottom of the tank.
Time and natural bacteria help these layers separate themselves out, though septic tank additives are also available to help aid in the process.
The septic tank is also connected to an inlet pipe, which is how wastewater from the house enters the system, as well as an outlet pipe, which allows wastewater to drain into the drain field, which further works to purify wastewater and redistribute it back into the soil.
How Is a Septic Tank Maintained?
The biggest piece of septic tank maintenance is periodically clearing the layer of sludge from the bottom of the tank. If this layer of sludge builds up too high, it can block either the inlet or outlet pipes, causing the system to stop working. There are many ways to check if your septic tank is full, but if you have a sludge backup, you may notice that you have trouble flushing the toilet or that your drains are draining slowly.
The good news? Most septic tanks only need to be emptied, or “pumped,” about once every three to five years. Your exact mileage between pumps will vary depending on the size of your tank, how many people are in your home, how much water you use, and whether or not you’re using high-efficiency appliances and fixtures.
On average, a one-time septic pump costs about $400, or $0.30 per gallon.
How Much Does a Septic Tank Cost?
The average cost to install a septic tank ranges from about $5,000 to $8,000, with the average hovering around $6,500. However, the cost of installing a whole new septic system can be much higher, between $10,000 and $25,000. The good news? With proper, regular maintenance, your septic system can last as long as 30 years.
Frequently Asked Questions
A septic tank should be emptied approximately once every three to five years, though this frequency will vary depending on your water usage, the size of your tank, how many people are in your home, and other factors. A maintenance plan for your septic system may be useful for professional emptying and inspection of other important parts.
When a septic tank is full, it needs to be professionally pumped. The average cost of a one-time septic tank pump is about $400, or $0.30 per gallon. If your septic tank is full, you may notice that you have issues flushing your toilet, pipes are draining very slowly, or you have a sewage smell lingering in your home or yard.
Yes! Toilet paper can be flushed if you use a septic tank. While unique toilet papers designed to be used with septic tanks are available, many people have no problem flushing regular toilet paper with a septic tank, so long as you don’t flush too much toilet paper all at once. Do not flush any type of baby wipes or bathroom wipes, even if they say “flushable.”