A Brief Overview of Septic Systems

Arc-18 leach pipe installation

What happens when I flush the toilet?

Let’s talk about septic systems. They are a major investment, and can cost anywhere from $5,000 to $30,000. Most people have a basic understanding of how they work. You flush the toilet, it flows out to your back yard, and magical gnomes carry away your effluent. Just kidding. It’s not a bad idea to have a basic understanding of how septic systems work and also know a few of the different types that are out there. Also, we will talk about simple maintenance that you can do on your current system to get as many years as possible out of it.​

Septic systems are generally made up of 3 components. There is a tank, a distribution box (d-box) and a leach field. The first place your sewer line goes is into the tank, which acts as a holding place for the solids that come from your house. Here the solids are broken down into effluent by bacteria that live in septic tanks. This effluent is a black water substance that is now able to leave the tank because it is no longer a solid but a liquid. The reason that solids remain in the septic tank is because there are baffles on the inlet and the outlet side of your tank. These baffles simply trap solids from exiting the tank and allow liquid to flow freely. If these baffles were not in place then solids would flow down into your leach field and ruin your system. They are a very important part of the septic tank. (In some special cases, there is also a pump tank that is installed after the septic tank. The pump tank simply houses a pump that pushes the effluent up to the distribution box. This would be necessary if the leach field location had to be at a higher elevation than the tank location.)

After the solids are broken down into effluent, they leave the tank and enter the distribution box. This little plastic or concrete box simply distributes the effluent out into the leach field. The reason the d-box is necessary is because it evenly distributes the amount of effluent into each leach line. There are generally “speed levelers” place into each leach pipe that leaves the box to ensure they are all taking the same amount of effluent. This way one leach line does not get overloaded and begin to seep out of the ground. The d-box also acts as another break up point for any effluent that may still not be totally liquefied yet.​

Distribution box in Palmyra, NY

After the solids are broken down into effluent, they leave the tank and enter the distribution box. This little plastic or concrete box simply distributes the effluent out into the leach field. The reason the d-box is necessary is because it evenly distributes the amount of effluent into each leach line. There are generally “speed levelers” place into each leach pipe that leaves the box to ensure they are all taking the same amount of effluent. This way one leach line does not get overloaded and begin to seep out of the ground. The d-box also acts as another break up point for any effluent that may still not be totally liquefied yet.

The last place your effluent goes is into the leach field. Here the effluent slowly dissipates into the ground. In order for this to happen, the soil in which the field is buried must have a good percolation rate. Percolation rate is basically how fast liquids pass through or are absorbed into the ground. You wouldn’t want to bury a leach field in clay like soil because it would just trap all the liquids and the system would fail. Generally, percolation tests are done before a septic system is ever installed. This is so that an excavator or an engineer can determine what type of system must be installed.

Now there are a few different types of systems that are commonly installed by excavators and plumbers. The most common and desirable one is a traditional infiltrator system. This system uses a special pipe called “Arc” infiltrator pipe. A number such as 18 or 21 follows the word arc. These numbers determine the width of the pipe being installed. So an arc-18 pipe would span 18 inches in width. These traditional systems can only be installed in locations where the soil has a good percolation rate. The arc pipes are buried usually six inches below the finished grade. This is so they can breathe and leach properly. If they are buried too deep then the system could leach poorly and result in a failed system.  These infiltrator pipes have replaced the old stone and pipe style leach field. They work wonderfully when installed correctly.

Another type of system is called a raised bed system. These systems become necessary when the soil at a certain location has very poor percolation rates. A raised bed system basically sits on top of the ground and is covered with sand. The effluent then leaches into the sand and the top few inches of soil. They can be very costly to design and build. Infiltrator pipes are often used as the leaching pipe inside the sand bed. There are various types of raised bed systems; one that should be noted is a Presby septic system.  The Presby system is less expensive and requires a smaller area for the leach field than standard raised bed systems. Only certified contractors are allowed to install Presby systems.

There are some other septic systems such as peat moss and aerobic systems. These are not commonly installed and so we won’t discuss them. We do hope you have a better understanding of how septic systems work and of the different types of systems that are available. Lastly, here are a few helpful hints to help you get many long years out of your septic system.

- Pump your tank at least every three years. Check to make sure both baffles are in place. If you have a newer tank, your baffle might be built into the middle of the tank. If you are unsure, ask the guy who comes to pump your tank. If you use a reputable septic pumping company, they should inspect it for you.

- Do not dump tons of bleach or anti-biotic down your drains. This can kill the good bacteria in your tank and cause solids to stop breaking down, which could cause your system to fail. Small amounts are OK.

- When you have your tank pumped, dig up your distribution box and inspect to make sure all the “speed levelers” are in place. Also make sure solids are not entering your d-box.

- Many female wipes and baby wipes say “septic safe” and “flush-able”. If you were on city sewer, I would say OK. Do not, however, flush these into your septic tank. They biodegrade over a very long time period, and can fill your tank up quite quickly.

-  I have heard coffee grounds are bad for septic systems. Maybe it’s because caffeine stunts the bacteria’s growth. Kidding. Dump your coffee grounds in the garbage.

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