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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.

For 86+ years, Van Delden Wastewater Systems has withstood the test of time as the leading Wastewater System company, providing San Antonio, Boerne, and the surrounding Texas Hill Country with services you can count on now and in the future. 

Call us for any of your wastewater systems needs and let our professionals help you with your septic installation and maintenance requirements: 210.698.2000 (San Antonio) or 830.249.4000 (Boerne).

29 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.

      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.

  7. My bathroom sinks are slow to drain. And the bathtub too, but only when running water through the faucet in the tub. My oldest son recently noticed that when he flushed the front bathroom toilet, that he heard something in the sink bubble, or air moving through it. I haven’t noticed any smells outside, but occasionally smell an odor in the house. Could be that I’m surrounded by boys. I also do daycare in the home. I had the tank emptied a little more than a year ago. I use a chemical flushing agent every couple of months, occasionally I forget.

    • Hi,

      Chemical flushing agents are not good for your septic system – even the ones that may not harm the system don’t help the system, so you don’t need to use any of those products. Even though you had your tank pumped about a year ago, the tank fills within a few days, then extra water flows to the drainfield. If your drainfield is not accepting your wastewater, this COULD be causing your slow drains. It could also be a blockage in the plumbing or in the sewerline between the house and the tank. In-home daycare’s tend to generate more wastewater than just a family living at the same residence. If your system is not able to accept your wastewater, it may be due to the amount generated and possibly surges on the system if you have to do a lot of laundry. You could either have a septic company or a plumbing company out – its kind of a 50/50 chance of which service type you need. If one type of provider comes out, they may recommend the other type of provider if they find no issues.

  8. Starting to get an infrequent back flow of water coming out the pipe our washer drains into (this is the lowest point in the house and connects direct to the outflow pipe) The water is clean and not sewage. The issue has only occurred 2 times in past month. Contacted a plumber who could not identify or replicate issue (ran a hose in the drain pipe and turned on faucets) and no back flow detected. He thought it might be related to septic. I pulled cover and noted holding tank water is full to the top, but not covering, the vertical portion of the liquid outflow pipe to the leech field. Could the recent extremely cold weather have caused my leech field to freeze and begin not accepting liquids? At a loss here, not sure if I should pump the tank, definitely not full of sludge, checked same. Help…….

    • Did this issue occur when you use the washing machine, or several loads of laundry at a time, or in the same time frame that other water was used (showers, dishwasher, etc)?

  9. This is my first time having a septic system. I know it’s a gravity with only 2 lines in the drain field. We had it pumped in October 2016. We have had a lot of rain and the septic over flowed into the green casing above the tank. We have that with the green round lid on top. I took the lid off today and I could see that after the days of rain it did come up into it. After taking the lid off the solid side the top was like a brick so I was able to break all that up and now it’s more like a liquid. I guess my question is because of all the rain and the drain field only having 2 lines could it make the septic over flow like that? Now it’s down not sure if it’s where it should be but it’s not near the top at all.

    • The green casing above the tank with a green lid sounds like a riser, which brings the lid to the surface of the ground. The normal operating liquid level in the tank is usually 8″-12″ from the top of the tank (not from the top of the riser). So, if the liquids/solids were in the green riser, then it sounds like the tank was overfull, which would indicate the absorption area was not accepting the water at that time. Rain can have an effect on the absorption area – especially if older and already “on its last leg”, but also consider your household wastewater usage. Since the level has reseeded some, I’d keep an eye on it. Monitor the liquid level when you use water regularly, when you do laundry and when it rains. Absorption areas usually are designed to have a certain amount of square footage…its not necessarily determined by how many lateral lines you have. I would suggest contacting a local septic installer either now or after you monitor the level in the tank for a while. Best wishes!

  10. After pumping our septic we could hear water draining into the tank, but we can’t find any leaks inside the house. I don’t know what to do now!

    • So, there was no water running inside the house at all at the same time that you heard water coming into the tank? That would be the most common reason for hearing water entering the tank. Other reasons may include (but not limited to): liquids flowing back into the tank from the drainfield, liquids flowing back into the tank from a leaking seam, etc.

  11. I been in my house for three years now and already had my tank flush two times already once every year and this year it will make the third time I would have to get it flushed because starting to hear the bubbling noises from the toilet when we take a shower or use the water in the sink. My question is why do I have to get my septic tank flushed every year and I have other people around me like 7 in the neighborhood that have septic tanks and the three years I’ve been here I haven’t seen none of them get there septic tank flush. And even people that I know that have septic tanks say they haven’t flushed a septic tank in about 7 or 8 years

    • If your system is functioning properly, you should only have to pump it every 3-5 years for maintenance. The fact that you are pumping every year due to the bubbling may mean you might have a great issue that pumping the tank isn’t solving, or you could have a blockage somewhere in the plumbing or between the house and the tank. For those that haven’t pumped their tanks in 7-8 years, it would be recommended for maintenance.

  12. I one month ago emptied the septic tank but today it is full if water again today and water came out

    • The tank will fill as soon as you use enough water in the house (usually a few days to a week). If water is coming out somewhere, then it sounds like the drainfield is not accepting the amount of water you are introducing to it. Pumping the tank again likely will not solve the issue.

  13. A small kid’s knit glove was flushed down an upstairs toilet two weeks ago. All’s been well so far. It’s a 3-bathroom house, two toilets upstairs and one in a far storage room downstairs. The downstairs one is not hooked up to water and never used, and it’s 10ft from the PVC sewer access cap sticking up in the yard. Now, when the upstairs toilets are flushed, this never-used always-dry downstairs toilet is suddenly filling up in the bowl with water and toilet paper, but no solids, and it’s leaking around where it’s seated on the floor. I opened the PVC septic cap in the yard and the water about 4 inches from the top. Did a small child’s glove create the problem in this third toilet. Or am I up against something else and more serious? Thanks for answers.


    I removed this third toilet bowl. When the upstairs toilets are flushed, I looked in the “hole” and see no backing up and can hear water rushing past smoothly and normally. But I do see a little water gathered down there when the flowing stops. This third toilet is about 10 – 12ft from the PVC sewer access cap sticking up in the yard. Opening the cap shows water level about 4 inches below the top, rising slightly with flushing then slowly settling back down. I am at puzzled as to why the back-up was at this far downstairs toilet nearer the sewer access pipe, but now everything flows through with this non-working toilet removed. I am leaving it removed for a while and temporarily plugging the hole with a Gripper Mechanical Plug. Is it okay to wait and see, or should I assume there’s still a blockage but near the sewer access cap and address that immediately? Thanks again for answers.

    • Its possible the glove could have caused a blockage somewhere. There should not be any standing water in the cleanout between the house and tank. Therefore, you may want to have a plumber check the pipe between the cleanout and tank, and the inlet baffle in the tank. You could “wait and see”, but if it were me I’d rather get a plumber out than chance a backup in the house, especially since the toilet is now removed. If no blockage is found then you may want to consider opening the septic tank to see if there is backup in the tank; which would indicate a larger problem with the septic system itself. Hope that helps!

    • Courtney Van Delden, thank you very much for your helpful answer. Yes, water is visible for a while between this 3rd toilet (now removed and plugged) and the outside access pipe. Water rushes through but settles then recedes slowly. The level in the outside access pipe rises to the top, but I hurriedly recap it before it overflows, which it seems certain to do. The house is among trees, so a root could be the problem. Present economy has me having to delay a bit, within reason, but I’m resigned to calling a professional. Would it be advisable to rent professional equipment (about $60+) and snake it through to see if I can clear out any blockage? I have a Ridgid Power/Spin but it’s 25ft and the distance is actually 30ft. Thanks again for the detailed response you gave to my question.

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