How Long Should a Septic System Last? Estimate Your System’s Remaining Time

Service technician opening septic tank lid. Cleaning and unblocking septic system and draining pipes.
A septic system’s lifespan should be anywhere from 15 to 40 years. How long the system lasts depends on a number of factors, including construction material, soil acidity, water table, maintenance practices, and several others. This lifespan projection assumes your septic system was properly designed and installed by a qualified plumbing professional according to the building code in your area.

If your septic system is getting along in years, then this article will provide you with good information you can use to estimate how many years it might have left. We will take a closer look at each of the factors that affect the lifespan of a septic system, and how you can get the most out of it. If you think your system needs a maintenance check, we’ll also review the best way to get that done, too!

Construction Material

One of the biggest factors involved in estimating the lifespan of your septic system is finding out what it is made of. There are several different materials used to construct a septic system, but two of the most common are steel and concrete.

  • Steel – 15-year lifespan

Steel septic tanks have the shortest lifespan of any septic tank, mostly because they are prone to rust. If you manage to get 15 to 20 years out of your steel septic tank, then consider yourself lucky. Before your luck runs out, and to prevent your steel tank from rusting out, it is important to have it inspected on a regular basis. A rusting septic tank can be dealt with if it is caught early enough before irreparable damage has occurred. So, if your steel septic tank is over 10 years old and has not been inspected within the last 6-8 months, don’t wait any longer. Call your local plumbing professional, Mr. Rooter, to conduct a thorough inspection of your tank and the entire system. We will be able to assess its current condition and give you a more accurate estimate of how much longer it should last.

  • Concrete – 40-year lifespan

Concrete septic tanks have the longest lifespan out of any septic tank material. While they are more expensive and sometimes difficult to install, it is for a good reason. A properly designed and installed concrete septic tank can last for anywhere from 40 years and beyond. As long as the pipes don’t clog or rust, and the tank was built out of quality concrete, there are usually no outside factors that will decrease the lifespan of a concrete septic tank. However, even a concrete tank should be periodically inspected to ensure no cracks have developed as a result of ground shifting or settlement and to confirm it is still in good working order.

  • Drain Field – 50 years

The drain field or leach field of a septic system is the series of pipes that branch off from the tank and disperse the waste therein. Without a properly functioning drain field, your septic system would quickly fill up and overflow into your yard which could cause a major health issue for people and pets that come into contact with any toxic waste overflow.

Pipes in your drain field system are usually made of PVC plastic, steel, or cast iron, which typically lasts up to 50 years if installed and maintained properly. Steel and cast-iron pipes should be inspected a minimum of once a year to confirm they are in good working order. And even PVC pipes should be periodically inspected to ensure they are functioning properly. The last thing you want to deal with is leaking or damaged pipes that contaminate your property and require expensive cleanup. Identifying a potential issue before it becomes a problem is the best form of proactive maintenance.

Related Topic: How Do I Keep My Septic System Healthy?

Soil Type

Another factor that can impact the lifespan of your septic system is the acidity level of the soil in which the system is buried. If your drain field is buried in hard, clay-like soil, it will make it difficult for the waste it carries to permeate and disperse into the soil. This can lead to clogs that eventually back up into your septic tank and cause it to overflow. Again, this can create a serious health issue that will need to be addressed. Therefore, if your tank is buried in soil that is hard or clay-like, it’s best to schedule maintenance and inspections more frequently. This is the best way to prevent an overflow, especially if you have a large family.

  • Non-acidic soil

Non-acidic soil is preferred when it comes to septic system installation. This is because acidic soil can eventually corrode steel, plastic, and cast-iron pipes. The same is true for your septic tank if it is constructed of steel or other material that is susceptible to corrosion. Systems buried in non-acidic soil see a marked increase in lifespan. So, consider your soil type when planning and scheduling routine maintenance and inspections.

  • Highly acidic soil

As mentioned, highly acidic soil will have a detrimental effect on the lifespan of a septic system. Concrete tanks will fare a little better than steel and plastic tanks, but eventually, highly acidic soil will take its toll on just about every system. Therefore, if you’re not sure what type of soil you have, or you're preparing to buy a home with a septic system, have the soil tested to determine the acid level. If the soil is highly acidic, schedule an inspection to ensure the system is in good working order, then schedule routine maintenance to identify any potential issues that may arise as a result of soil acidification.

Water Table

The water table refers to the top layer of water beneath the surface of the soil, and it must be low enough for wastewater to be able to filter into the soil. If the water table on your property is too high, then the soil is unable to absorb water from the drain field. With nowhere to go, the water will back up into your septic tank and inevitably lead to the entire system overflowing.

If you live in a floodplain or low-lying area that is susceptible to frequent flooding, the soil around your home may have a high water table. This could result in more frequent backups, which will drastically shorten the lifespan of your septic system.


It’s only logical that the more usage your septic system is subjected to, the sooner it will need replacement. There’s a big difference between two people using a septic system and four people using it. However, the extra demand and strain put on a system that is used by a large family are lessened for a system that is well-maintained with frequent service and periodic inspections.

Related Topic: How Often Should a Septic Tank Be Pumped Out?

Routine Maintenance and Inspections

By now you may be sensing a common theme to septic tank longevity. One of the best ways to extend the lifespan of your septic system is with periodic inspections and professional maintenance. Whether you’re purchasing a new or older home, or have lived in the home for several years, regular maintenance and periodic inspections provide the peace of mind that comes with knowing your septic system is in good condition and working properly. So don’t wait for something to happen, call your local Mr. Rooter today to schedule an appointment.