A septic tank is a watertight container, made from reinforced concrete or traffic-rated plastic. It is typically located right outside the home, buried completely underground. Newer septic systems will often have risers installed on the septic tank allowing easy access for septic pumping, inspections, and repairs. A typical septic tank can hold 1,000 gallons and is approx. 5 foot wide by 9 foot long with a depth of 4 1/2 foot.

What Happens in the Septic Tank?

septic tank illustration - tw ammons septic service 2017

Septic Tank Illustration, T.W. Ammons Septic Service, Inc. 2017

Like many other tanks in life, a septic tank’s sole purpose is to hold stuff. For the septic tank, that means septic waste water and solids, or as the kids say, “poop.” The septic tank is split into two functional sides: the inlet and the outlet. Separated by a baffle wall, the two sides only allow liquid to cross in the middle. By breaking down the waste and the toilet paper into three layers – as seen in in the septic tank illustration above – the outlet end of the tank only allows liquids to enter the septic drain field lines.

Everything converges from your house into the inlet end of the tank. While held, the entirety of waste goes through an anaerobic process. The top layer is referred to as the “scum” layer and consist of toilet paper, lighter solids, and any grease, fats, and oils. The middle layer is the “liquid” layer. The bottom layer is known as the “sludge” layer and contains most of the solids.

The septic tank further protects the septic drain field lines by using a sanitary tee. Newer tanks are outfitted with a filter that guarantees only liquids leave the septic tank. But because of this, it is very important to have your septic tank pumped.

What Should Not Be Put into the Septic Tank?

As a general rule, “Only flush what makes you blush!” That means human waste and septic-safe toilet paper. The ultimate test for septic-safe TP is to take roughly 5 sheets of toilet paper and place it in a jar or other container with a lid. Shake it up and if the paper is shredded it’s septic safe.

Three big NO’S (NSFS – Not safe for septic!):

1. Don’t pour cooking grease, fats, or oils. These will harden and impede the intended flow of wastewater. In a worst-case scenario grease, fats, and oils can cause your drain field to stop working completely.

2. Don’t pour chemicals. Anything you find under your kitchen sink should STAY there. In a septic tank and drain field, chemicals can reek havoc. This includes pesticides, paints, paint thinners, solvents, disinfectants, and poisons. No one is judging why you have poisons, we’re just saying keep them out of your septic system!

3. If you have a water softener hooked into your house, make sure it doesn’t discharge into the septic system. The backwash is very harmful to the structural integrity of the septic tank and will kill the good bacteria in a drain field.

Will I Need to Have My Septic Tank Pumped?

  “An ounce of prevention is worth a pound of cure.”

Yes. If not, the solids collected in your septic tank could find their way into your septic drain field. This creates biomat, rendering your drain field ineffective at water filtration. When water is unable to filter through the soil, it will back up in the drain field. This causes waste water to pool in your yard above the leech lines, and can also cause sewer backup in your home.

In other cases where your septic tank may have a sanitary tee with a filter, a septic tank that needs to be pumped can lead to waste water back up in your home. So now the question becomes, when do I have my septic tank pumped?

When Should I Have My Septic Tank Pumped?

“The tank should be pumped if the sludge layer at the bottom of the septic tank has built up to within 25 to 33 percent of the tank’s liquid capacity or if the scum layer (top) in the tank is more than 4 to 6 inches thick.” – NC State Extension Publications

When to pump your septic tank is usually discovered in one of two ways. With the first, your chosen septic service professional checks the septic tank during a routine maintenance. With the second, you simply note your water usage. According to the Journal of Environmental Engineering, pumping frequency is as follows:

1000 Gallon Septic Tank – Suggested Pumping Schedule

  • 1 PERSON – Every 12 Years
  • 2 PEOPLE – Every 6 Years
  • 4 PEOPLE – Every 3 Years
  • 6 PEOPLE – Every 2 Years
  • 8 PEOPLE – Every Year

1500 Gallon Septic Tank – Suggested Pumping Schedule

  • 1 PERSON – Every 19 Years
  • 2 PEOPLE – Every 9 Years
  • 4 PEOPLE – Every 4 Years
  • 6 PEOPLE – Every 3 Years
  • 8 PEOPLE – Every 2 Years

Having a garbage disposal will cause the septic tank to need pumping more frequently, depending on its usage.

When getting your septic tank pumped, below are two things to remember:

1. Have your pumper check your septic tank’s filter. On newer systems it will have a plastic tee with a removable filter that needs to be cleaned. On older systems a 4” PVC tee will be used and should be rinsed off. In other older systems the use of a cement baffle tee was common. It is important that the septic pumper checks the cement tee for structural integrity. The tee can over time become brittle and ineffective.

2. Have your pumper pump both compartments of the septic tank. These are commonly called the “inlet” and “oulet” sides of the tank. While the inlet is absolutely necessary, the oulet is also good to have pumped. A tank can have solids enter the oulet end of the septic tank if too many years of use have passed without pumping.

Now that you know more about the septic tank and septic systems, we suggest you keep a file along side all of your other household maintenance schedules. It is incredibily helpful for any future septic system service and can save you money!

While T.W. Ammons Septic Service, Inc. does not pump septic tanks, we can help you find a reputable pumper in your area. And if you’ve had your septic tank pumped and are still experiencing slow drains, or standing water in your yard, we are here to help fix your septic system.