“You just came out two weeks ago and pumped my septic tank but it is still full. Why?” This and several variations of the question have to be one of the most common questions I hear.

I confess before my husband and I bought this business many years ago I could have cared less how the septic system worked. All I knew was when it worked property the household functioned “fairly normally”, but when the system backed up chaos rained throughout my “civilized world”. There is nothing worse than cleaning(#@!*) sludge out of the bath tub, off the bathroom floor, or when you have a cesspool in your back yard, not to mention what happens when no one can shower or use the toilet.

So to answer the question of why your septic tank is full soon after is has been pumped is because it’s designed to work when it’s full and maintained properly. If you have 1,000 gallon septic tank once you use 1,000 gallons of water it will be full and continue to remain that way unless there is crack in the structure.

Here is a basic diagram of what a septic system looks like: 

As you can see both inlet and outlet pipes are at the top of your septic tank. As you use the plumbing in your home water and solids flow into the tank. The solids settle at the bottom of the tank and as bacteria breaks down the solids a layer of “scum” floats to the top leaving the gray water in between. A the tank fills the gray water enter the outlet pipe and flows into the leach field, but over time the layers of “scum” and solids continue increase.

Backups occur when solids, toilet paper, obstacles that don’t belong in a septic tank or roots block the outlet pipe and the sludge has no place else to go but inside your home. Leach fields fail when the solids and scum have filled the septic tank to the point they have no place to go but out the inlet and outlet pipes. Leach field can also fail when an excessive amount of water is used and floods the leach bed. When l say “excessive” I am not referring to the normal plumbing and washing machine use. After pumping a customer’s septic tank we were called back out two more times because of back up. It took a little probing but it turned out the customer was doing laundry for several of her neighbors.

Roots can also invade the system and cause damage to the point of failure for both septic tank and leach field. Avoid planting trees such as a cottonwood if you have a septic system and never, ever plant a rose bush where there is that nice patch or green grass or over the leach field. I promise you will have problems in about two years when that bush starts to grow like crazy.