How Long Does a Septic Tank Last? Practical Tips to Make Yours Last Longer



If you’re reading this, chances are, you are purchasing a property from someone, have an idea on how old the property is, and are trying to decide whether to install a new aerobic septic system or retain the old one. Another possibility is, you’ve had your septic tank for a while now, and you don’t think it functions properly anymore; thus are confronted with the need to decide whether to go for a quick repair or replace it altogether.


How long does a septic tank last?


An aerobic septic system typically lasts between 15 to 40 years. Many factors affect the life expectancy of your system hence the wide range.


The life expectancy of the septic tank largely depends on the material used and the quality of construction. Currently, there are four types of materials used for septic tanks: concrete, steel, plastic, and fiberglass. Of these materials, the most durable is fiberglass and offers the longest life expectancy.


The life expectancy of the septic system depends primarily on factors as vehicle traffic, flooding by groundwater, and the clogging of tree or plant roots.


Types of Septic Tank Materials

There are four types of septic tanks based on the material used.

  • Concrete septic tank. Of the four types of tanks listed here, the concrete septic tank is the heaviest. To ensure durability and a speedy installation, usually, concrete septic tanks are precast. The concrete used in this type of tank has a specific gravity measure of 2.40 to withstand the buoyant forces it will be subjected to once installed in the ground. What is remarkable about the concrete septic tank is that their strength increases over time when correctly done. Concrete septic tanks can last for many decades and are strong enough to withstand damage from heavy machines during maintenance operations. In addition, because they are heavy, they won’t float if the table goes up to the tank level.
  • Steel Septic Tanks. This type of tank is probably the least popular because it is expensive and not as durable as the other types of tanks. They are prone to damage and corrosion over time and have the least life expectancy. In addition, it cannot resist the weight on its top. Thus, the chances of collapse are high. During maintenance operations, too, one needs to be careful as they can sustain damage from heavy machinery. 
  • Plastic Septic Tanks. This type of tank is the lightest. Most plastic septic tanks are made of polyethylene terephthalate. Thus, plastic septic tanks are also called poly septic tanks. Plastic resists damage and corrosion; therefore, it may last long, too. However, because plastic has a specific gravity of 0.97, less than water, it may float if installed at a depth near the water table. 
  • Fiberglass Septic Tanks. Fiberglass Septic Tanks are almost similar to Plastic Septic Tanks, only that they have higher durability than the latter. The material used is usually fiber-reinforced plastics (FRP), thus making it more durable than plastic septic tanks. The very disadvantage of this type of tank is that it’s lightweight and would float during a flood. 


Septic Tank Service



Another factor that determines how long a septic tank will last is the septic tank service. Regular maintenance will boost the longevity of your septic tank. 


A typical septic tank needs to be pumped at least every 3 to 4 years. Additionally, a regular tank inspection will reveal any need for repair or additional maintenance. Good maintenance includes pumping and removal of clear waste, inspection, and removal of scum. Regular maintenance increases the life of your septic tank significantly.

How Long Does a Leach Field Last?



Aside from the tank, the aerobic septic system also has a leach field or a septic drain field which may dictate the life expectancy of the entire system. A leach field is where the liquid from the septic system drains, and the contaminants and impurities are removed. 


Many factors determine the life expectancy of a leach field, including its size, usage level, and soil percolation rate. Typically, a sufficiently large drain field with a reasonable soil percolation rate could last about 50 years or more.


Make Your Septic Tank Last Longer


Although most of the things that determine the longevity of the septic tank and system are beyond our control, some things can be ensured and maintain to make yours last longer. Here are some things you can do:

  • Select the best quality and design. When we speak of the best quality and design, it’s not like there’s one design that could fit all that is the best. Factors such as soil condition, location, and installation all contribute to the quality and lifespan of your system. Avoid installing our tank in an area prone to flooding and has a high water table. Also, select a location where soil condition is compatible with being a leach field.
  • Select your septic tank material. A list of tank materials is already listed above. Concrete, plastic, and fiberglass are durable materials for your tank, but each has its sets of advantages and disadvantages. Select which is the best for your location, soil type, and water table height. If possible, refrain from choosing steel tanks. Steel tanks are prone to rusting. Often, they deteriorate sooner than expected.
  • Choose the correct tank size. Tank size should be based on your household use. A smaller tank size compared to household use means that your tank is prone to flooding and may need maintenance more often than it should be. In addition, a frequently flooded leach field may reach the end of its lifespan sooner, too. If you can’t do something with the tank size, reduce the septic tank workload instead.  
  • Have a professional team service your septic tank regularly. Regular inspection and maintenance ensure that your tank is rid of solids that may clog and damage not only your tank but the rest of your septic system, tool. Regular maintenance should involve inspection and pumping, if necessary, to extend the life of your septic tank. Professionals are trained and experienced in spotting mistakes and issues with your tank and system long before they lead to potentially serious problems. They also know the exact measures to take to deal with the said issues.


Will an unused system become usable after many years?

Like all other things, a septic system is prone to wear and tear over prolonged periods of use. Its life could further be shortened or extended by how extensive that use is. A septic system can sit unused for 30 to 40 years without being used and will still be fine. Such a long duration, however, offers many possibilities. It’s better to have the septic system checked by a professional to ensure that things are working correctly. 



The lifespan of a septic system or the septic tank depends on factors such as the extent of use, the materials used, design and location, and the frequency and quality of inspection and maintenance.


A septic system is designed to process both solid and liquid wastes. Heavy use of the septic system offers the possibility of flooding and clogging unless maintenance is done frequently. Additionally, the amount of water that goes into the tank must be minimized–if possible, optimized. Too much water can flood the drain field and can compromise the entire system.


Tank material also plays a crucial role in the septic system’s longevity as the tank holds the waste processed in the system most of the time. There are currently four common materials used: concrete, plastic, fiberglass, and steel. Of the four, concrete is the most durable and can handle areas with a high water table. Plastic and fiberglass are as durable but are cheaper. The only downside is that they are not heavy enough during flooding, so they must be installed in areas not prone to flooding. Steel tanks rust out and don’t last as long as the other materials. 


An essential process that a septic system does is draining the liquid waste into the drain field. Thus, location is a critical factor in this process to take place successfully every time. The perfect location for this is an area with good quality soil that can absorb liquid waste fast and is not prone to flooding. 


Lastly, to ensure that your septic system and tank last long, a regular inspection and maintenance by a professional team needs to be done every 3-4 years, depending on the extent of use and the size of the tank. It’s essential to undergo an initial inspection to decide on the inspection and maintenance schedule as early as possible.


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