Is your septic tank full?

Frequently we get phone calls from folks saying “I lifted the lid and the tank is completely full”. Completely full can mean allot of things. To me completely full is just that, full to the top of the lid. If you put anymore in, it would spill over. If that is the case, you definitely have a problem. If you have too much space between the top of the tank and the top of the sewage, you likely have a problem also.

Under normal working conditions, there is some space between the top of the tank and the top of the sewage in the tank. This allows for venting from the drainfield as well as room for surge when you drain a large bathtub or do a bunch of laundry at once (which you really shouldn’t do). There should be about eight inches of space there give or take a couple of inches.

The septic tank needs to have liquid in it in order to function. Without getting into too much detail, when the poo comes into the tank, the light weight stuff (toilet paper, fats and oils, etc.) floats to the top and becomes the scum layer. This is where most of the bacteria do their work, breaking down the poo, paper and what not. The heavy stuff (by products from the bacterial action, heavy metals from shampoos, etc.) becomes the sludge layer on the bottom of the tank. This leaves the clear zone in the middle of the tank. I think “clear” is a relative term!

If the tank is full to the point of spilling over, you may have a drainfield problem. It could be a line plugged from the tank to the drainfield, or if you have a pump in the system, some electrical or mechanical failure. If the tank is too empty, it is likely cracked or broken and leaking sewage out in the ground untreated. Steel tanks will rust out. Plastic tanks can collapse. Fiberglass tanks can crack. I have also seen cement tanks that were deteriorating from the inside out. It’s not common, but it does happen.

Back to the “stuff” in the tank. The longer you go between pumpings, the more sludge and scum build up in the tank. This decreases the clear zone in the tank. That is a bad thing. In the clear zone the small particles settle out and fall to the bottom, keeping it from drifting out into the drainfield. If the little particles get into the drainfield it will eventually cause failure which will lead to the “my tank is full” and coming out of the top situation.

How long is too long? It depends on how many people are using the system, how many hours they use it each day. In other words, do you go to work or school, or do you stay at home all day? It also depends on how you use it. Do you do allot of laundry? Is someone in the house on Chemo or heavy antibiotics? Do you use allot of bleach? How about the in sink disposal? All of these things can have a detrimental effect to the bacteria in the tank, which can reduce time between pump outs.

For the average family, the EPA recommends inspecting your tank every three to five years. If you have a riser on your tank, that is an easy process. We have a tool called a Sludge Judge. This tool takes a core sample of the tank. It is recommended that you pump the tank when the solids level reaches approximately 30% of the capacity of the tank. If you don’t have a riser on your tank, the lid will have to be dug up for us to check it. Usually if a person has taken the time to dig up the tank, they want us to pump it out. At that time a riser can be installed so it can be checked more easily next time.

When we pump your tank we can see how well the bacteria is working. We will also check to see if the baffles are in place and the tank is in good condition. Usually if there is a problem with the poo getting out of the tank it will be evident to us too. At this time we will recommend when the next pump out or inspection should take place. When the time comes we will send you a reminder in the mail. If you would rather us to e-mail it, be sure to provide us with the proper address to send it to.

In summary, yes your tank is full, but does it need to be pumped? That is the important question. Give us a call at 503-829-7448 to schedule a pumping or talk about proper maintenance. You can call to just say “Hi” if you want! Of course our web address is

We are on Facebook (Clinkscales Portable Toilets & Septic Service) and Twitter (@ClinkscalesSptc), if you have questions or comments feel free to post them at either place and we will get back to you. We also run specials and contests occasionally so check in often!




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