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Help! My Septic Tank is Full!

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Normal septic tank level

We often receive calls about “full” septic tanks. But what does full really mean?

A septic tank should always be “filled” to its normal liquid level, or the bottom of the outlet pipe which carries effluent to the absorption area. This normal liquid level is usually between 8” to 12” from the top of the tank on average (see picture at right). If the liquid level is at bottom of the outlet pipe, then one would assume the absorption area is accepting the household wastewater.

If the liquid level in a septic tank is above the outlet pipe, or to the top of the tank, we call it “overfull” because the tank is filled above its normal operating level. If the tank is overfull, this is usually a sign of problems with the absorption area.

Plumbing or septic issue?

We have a lot of people call us to pump their tank because they say it is full…usually because they are beginning to experience problems. Sometimes, though, the problem is actually with the plumbing. How can you tell if a problem can be solved by your septic maintenance provider or a plumber?

Check the cleanout

If the problem is due to backup in the house, we recommend checking your cleanout between the house and the tank (if one is present and accessible) to see if there is any backup in the cleanout (usually a 4” PVC pipe that has a removable cap).

If the cleanout does not contain any backup, then we usually recommend contacting a plumber, as this indicates the wastewater from the house is not making it to the cleanout.

If the cleanout does contain backup, then it’s a 50/50 chance it may be the septic system. This can then be determined by exposing the lid(s) of the septic tank and checking to see if the liquid level is normal or overfull. If it is normal, we usually recommend calling a plumber. If it is overfull, then you may have larger issues (i.e. the absorption area).

If you do not have a cleanout, then your chances may be 50/50 whether a plumber or septic company is needed and you won’t know until one of the two are called to check it out. If you can look directly inside your tank to determine your liquid level, this can help guide you to calling the right service company.

Check for smells

A bad smell in the house usually indicates a venting or plumbing issue. If you are not experiencing any backup inside the house or any problems outside the house with the septic system, we recommend you call a plumber.

Signs of a larger problem

Overfull septic tank

Depending on the size of tank and number of the home’s occupants, a septic tank will usually fill back up to its normal liquid level after it has been pumped out within a few days to a week. Once the tank fills back up to its normal liquid level, then effluent begins to enter the absorption area again.

If the septic tank is “overfull” this may be a sign of a larger problem with the system (see picture at right). In this case, pumping out the septic tank will give some temporary relief, but will usually not solve the problem long-term.

If the absorption area isn’t accepting the amount of wastewater your household is introducing to the system, then you may experience the same problem again, which may indicate that your system is in need of repair or replacement.

Download a free copy of Understanding and Maintaining Your Septic System to learn more about septic system maintenance.


14 thoughts on “Help! My Septic Tank is Full!

  1. We moved in a year ago. Its the first time we’ve had a septic system. How do we care for it? How often should it be pumped out? One person lived here for 8 yrs. Now there are two.

    • Great questions! There’s a lot of information to answer your questions, so forgive me for referring you to our FAQ page, but I think it will be the most helpful useful. http://www.vdwws.com/faqs/frequently-asked-questions/

      Check out the FAQ’s for Septic Systems and Septic Tank Cleaning on that link. If I can clarify anything, please don’t hesitate to message me again!

    • It depends on the pumping company, local regulations, and what type of treatment is available. Our company takes the wastewater from our trucks to the San Antonio Water System Dos Rios Treatment facility. This facility is where most of San Antonio’s sewer waste gets treated, but they also have a dump station for vacuum trucks. This is the only place locally where we can dump our trucks. If you want more information on other types of treatment, you might want to Google “dewatering” and “land application” as it relates to septic waste. Best of luck with your project!

  2. My septic tank has to be pumped monthly, what could be the issue? I am a medically retired Army service member and never had to deal with septic tanks so needless to say I need advise. Please respond

    • In general, you shouldn’t have to pump your septic tank that often unless you are having a problem with your drain field. This usually leads to extensive repairs, however there are many situations and factors that could arise. You might want to check for leaks in the house that may contribute to the drain field flooding out too. It would be a good idea to contact a local septic company to see if they can help determine what may be causing the issue.

  3. my septic tank started to have sewage water flowing out of the vent pipe thus also smelly since feb 17 after moving in for 2.5 years.
    I suspected the ground is not absorbing well as during construction, there were 3 houses constructed along the same area and i could see water not draining fast during construction.
    What can i do to prevent this hygienic issue?
    The last resolve is to make another much bigger septic tank.

    • In most cases, what you are describing may be related to how well the absorption area is accepting wastewater and how well it can percolate through the soil. This could be due to the soil type, system type, design or even your household wastewater usage. Be sure you don’t have any extra water going into the system such as a dripping faucet, running commode or malfunctioning water softener as these could cause the system to flood out. A larger tank itself probably wont solve your issue as its more than likely a drainfield-related issue.

  4. We moved into our house a year ago. We are a family of four, take a lot of baths, have guests a few times a year, and have recently had a lot of rain in our area. The previous owners had the tank pumped in October 2015. Earlier this week, we had gurgling sounds coming from our shower drain when we flushed the toilet and water backing up into the shower drain. My husband snaked a hose into the vent and then found backup in our venting system. When we got the tank pumped it was full to the top. The guy who pumped it said that wasn’t typical and thought we had an issue going out to the galleys. We got a second opinion and this guy told us the pipes going to the galleys were fine, he thought the problem was that the pipe coming from our house had sediment built up inside it from the pipes being old (the house was built in 1970), and we needed to jet the pipe and de-scale it. We have no sewage smell or soggy areas where the galleys are located. My question is did our tank just need a routine pumping, or was the back up caused by a larger issue. Thanks!

    • That’s hard to say. By pumping the tank the first time, that may have altered what your 2nd opinion guy saw. The liquids should not be backed up to the very top of the tank – as this does indicate a problem with your drainfield (I think you are referring to as galleys?). But while the tank is still filling up, it gives your drainfield a little time for recovery. Some drainfield recover for short amount of time, some don’t. But if the liquid level was normal when the 2nd person arrived, then he would probably assume the drainfield is working and your backup must be from an issue before the tank. If you experience a backup again, have the tank checked and if the liquids are touching the top of the tank then the drainfield is not accepting your water. Sometimes you don’t have a sewage smell or soggy areas when a system is failing. You could follow the advice of the 2nd person and try to clear the pipes as a precaution. But it may take trial and error, and time using the system, to figure it out for sure since you have two different opinions.

  5. Does the aerator pump on a septic system stay running 24/7 or does it cycle on and off? And if I can’t see the 90 on my drain pipe, but do see the drain pipe in my first chamber, is my septic full? And does it need to be pumped?

    • Yes, the aerator pump needs to stay running 24/7 – the aerobic bacteria cannot survive without the oxygen the aerator pumps into the system. If you don’t have bacteria, then you don’t have treatment of the wastewater. It’s not exactly clear which pipe you are referring to in your second question. Pumping is not usually based on the water level in the system unless you are having a problem causing back up in the tanks. Pumping is usually based on sludge levels, which should be checked by a professional.

  6. We constructed a septic tank at one of my school’s projects. Before the ablution facilities were utilized the septic tank was already 75% full of water due to some plumbing issues which caused water from the borehole to be drained straight away into the septic tank instead of the water being retained into the toilet cisterns. We are requesting the contractor to pump the septic tank but he is insisting that a newly constructed septic has to have water for operation purposes. Please assist what do we need to do?

    • I’m a little confused by your situation, so I will answer in general terms. Lets say the tank was empty right now, as soon as the facilities are used, that water/wastewater will fill the tank to its normal operating level, then any additional liquids would flow into the distribution area. So yes, in a sense, the tank has to be filled for the system to operate. Locally, our regulations sometimes require us to fill the tank for the county inspections. So, the fact that the tank has water should not affect the system. My suggestion would just to be sure there isn’t anything in the tank that cannot be pumped later or that might affect the ability to treat the wastewater (oils, grease, trash, etc.). Not sure what kind of sediment or how much may have gotten in there. That may be something worth pumping now or whenever the tank is pumped in the future. Perhaps you should have a 3rd party person take a look and give you recommendations.

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