What Happens When Septic Tank is Full? 9 Signs

Do you own a house having a septic tank and worried about its being full? If so, then you are in the right place.

There is a misconception among homeowners that septic tanks do not need pumping or treatment, which is not true. The Septic tank requires pumping after a certain period. But when to do that?

To make your job easy, we have outlined 9 signs that your septic is full. If you experience any of the below-mentioned issues, you should consult a professional to have your septic system inspected, and pumped if necessary.

9 Signs Septic Tank is Full

If you want your septic tank to function properly for a longer period, it is best to know the signs septic tank is full. Without knowing that your septic tank is full, you cannot take precautionary measures correctly. Following are the signs indicating septic tanks are full, and you need to call a professional to fix it.

what happens when septic tank is full

Unpleasant Smell or Odors

Foul smell coming from the septic tank is usually the first sign to show that the septic tank is almost full. If the septic tank is full, it may start to affect performance due to clogging, overflow, and spare waste.

All of these issues can cause an unpleasant sewage smell and may start to seep into your property or the land around the storage tank. So, never ignore the septic tank’s unpleasant odor because it can lead you to trouble in the near future.

Slow Drainage

When your septic tank is full, it may cause slow drainage or trouble in flushing. This is due to the reason that sludge (solids in the bottom of the septic tank) may clog your drainage pipes which in turn cause slow drainage.

Slow drainage can be caused by multiple issues, not just a full septic tank. But if you face the problem in more than one pipe, then it is almost sure that your septic tank needs to be emptied.

Bubbling Sound of Water

The bubbling sound of sewage water is another alarming sign that your septic tank is full and needs to be emptied. That’s why; if you face any gurgling or bubbling sound of sewage water, please do not ignore it. This is the indication that your septic tank needs to be emptied.

The sound comes from the toilet, especially after using it.

Leaky Sewage Pipes

When your septic tank is full to a maximum level, it starts to overflow. The extra waste material is clogged in pipes, and the leakage starts in pipes.

This is the most intense sign that your septic tank needs to be cleared out. Therefore, if you find any leakage in your sewage pipes, make sure to have the system inspected by professionals.

Back Flushing

If you ignore other signs that the water storage tank is full, raw sewage may begin to flow back into your house through the sink and bathtub.

Septic tank waste is a major health hazard, and this is a problem that you must deal with as soon as possible. The water or other waste material starts to flush back into the pipes. Backflushing is the most unpleasant sign of a full septic tank.

Overly healthy grass

Like standing water, the outer area directly surrounding the septic tank may show signs of overflow or leakage. If the grass covering the septic tank is much greener than the surrounding lawn, you may have a problem to solve. Sadly, in this case, being too green means that there is too much to feed the grass, and you may have an overflowing tank.

High Nitrate Content in Well Water

High nitrate content in the well water is also an alarming sign that septic tanks are full. You can also check your septic tank level by monitoring the well water’s nitrate content.

The higher the level of nitrogen in the well water, the higher the septic tank level. So, nitrate content test is also a great way to find if you need to act or not.

Trouble Flushing

When you notice any trouble flushing in your house, it is maybe due to your septic tank not having enough space for the air to circulate. While this may happen due to a faulty flush, it is worth checking the septic system’s health before anything unpleasant starts to happen.

Pooling Water

When the septic tank is loaded in its capacity, you will start to notice water accumulation in various places around the yard. The most common place where this happens is the area around the septic tank and/or drainage area. If there is too much solid waste in the septic tank, the sludge will move into the pipes in the drainage zone.

Once solid waste blocks these pipes, the drainage area will not work properly. When water enters the field, it will not flow through the pipeline as designed but will accumulate in a specific area.

If you have standing water in these areas, this indicates that you need to clean the septic system immediately and inspect it.

Ask a Professional

Actually, the septic tank contains three layers. The bottom is called sludge, and it contains solids. The medium layer is made up of water, while the third layer comprises fats and oils, known as scum.

Only a professional can tell you the right level and percentage of each layer. Therefore, it will be best for you to ask a professional to correctly know that your septic tank is either full or not.

Read: Do Septic Tank Freeze?

Why is it Important To Maintain Septic Tank?

To avoid future troubles related to sewage that causes a bad smell and an unclean environment, it is necessary to keep track of your septic tank.

Therefore, the best way to know when the water tank needs to be emptied is to set a schedule, and it’s a simple but effective solution. If you can determine the proper emptying interval, you may not even see any of the above warning signs. 

Moreover, the emptying intervals depend on the size of the septic tank and the number of users. Consequently, the Environmental Protection Agency recommends emptying the septic tank every 3-5 years. However, the exact time varies from place to place and depends on various factors. If you want to delay the septic tank pump for a year or so, you should plan in from day one and use septic tank treatments regularly.

Read Our Guide on Septic System Maintenance


In a nutshell, if you want your septic tank to function for a longer period, it is best to pump it in regular intervals. People often try to go with other routes than the pumping to save money but when they think about it, it becomes late.

The alarming signs of a full septic tank include foul-smelling, overly healthy greenery, slow drainage, trouble flushing, leakage in sewage pipes, backflushing, etc.

We recommend consulting professionals if you face any unusual activity relating to the septic system. This will save you from unpleasant experiences.

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