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01. How A Septic System Works

Poly Septic tank, plastic septic tank installation in Sedalia, Colorado by John Todd Company

     If you’ve ever seen the Pixar film “Finding Nemo”, you are probably familiar with the idea that “all drains lead to the ocean.” For us here in Colorado, or any of the other land locked states, there is a cheaper solution than running pipe for thousands of miles just to pollute the ocean. In fact, there is a much more “green” way of getting rid of our dirty water: septic systems.


     For those who live outside of the city, or if you live in a home that was built decades before the city was built around you; you probably rely on a septic system.  A septic system is an On-site Waste-Water Treatment system that is designed to keep you from having to use a shovel in the back yard! This means that all drains in your house lead to a small concrete (or plastic) container buried in your yard; this is called a Septic Tank.


Septic Tank Diagram Septic System Septic Tank Install How a septic tank works

      Some systems use several septic tanks, and they range in size depending on how many gallons will be used in the house. This diagram shows a basic two compartment, single septic tank system. The septic tank has two compartments: a larger compartment where all of the solids (i.e. feces, toilet paper, all the fun stuff) are held, and a small compartment that is used to hold the water that is separated from the solids. This is a key process; otherwise your septic tank would fill up in under a month with how much water is being used.



     The two compartments are separated by what is known as a Baffle Wall. Over time, all of the solids sink to the bottom of the first compartment, while the water floats above it. After awhile a “scum layer” will develop on top of the water, this is all of the small particles that are lighter than water and float at the very top (Fats, oils, etc.). The purpose of the baffle wall is to keep both the solids and the scum layer in the first compartment while letting the water flow into the second compartment.

Installation of plastic poly septic tank in Littleton, Colorado by John Todd Company

     After the water is separated, the water flows down an outlet pipe to the Leach Field (also known as an STA or Soil Treatment Area).  There are many types of leach fields and there are many ways of getting the water to the leach field. Some use gravity and flow “downhill” to the leach field, others use a pump system to get the water there. No matter how it gets there, the purpose of a leach field is to spread out the water across a specific amount of soil (all under ground). Once the water is spread out into the soil, bacteria will eat all of the small particles of septage (all the dirty particles) and by the time the water reaches the aquifer it will be pure again. The size of leach field (and size of septic tank) is determined by how many bedrooms are in your house. The more bedrooms, whether occupied or not, leaves potential for another person to be using more water.

Installation of a gravity leach field in Castle Rock, Colorado by John Todd Company

 The next process is getting rid of the solids. This is also very important for sustaining the life of a septic system. If the solids build up too high, they will flow into the second compartment of the tank, and from there to the leach field where it can plug the pipes and not let water drain out. When this happens, the water will find the path of least resistance, which is usually back into your home! To save yourself from needing an emergency pumping or having to install a new leach field, we recommend for a family that uses their system regularly that you get your septic tank pumped every two years. If it’s a system that isn’t used often, or at the very least, county requires that your septic tank be pumped every four years. If you’re not sure when you were last pumped or your two years are up, give John Todd Companies a call and get your septic system pumped!


Feel free to call the office at 303-791-0520 if you have any questions.


Thanks for reading!


Jesse Todd

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