How Long Do Septic Tanks Last and When Should You Consider a Replacement?
Septic systems have seriously stellar life spans
Highlights
Septic tanks last 20 to 40 years, on average.
Materials, ground type, and maintenance can all impact their life span.
A soggy line, clogs, and sewer smells are signs your septic tank is worn out.
Septic tank replacement ranges from $3,000 to $10,000.
Septic tanks are a stinky yet essential part of a home’s wastewater system if it’s not connected to a public sewer system. Buried deep under the ground, they’re often forgotten about or ignored until something goes wrong or it’s time for maintenance. If you’re curious about whether your home has a septic system or not, property records, signs in your yard (like a large rectangular cover), or a professional inspection can let you know. If your home has a septic system, learn some need-to-know details about septic tank functions and how long septic tanks last, on average.
How Long Does a Septic Tank Last?
The good news is that a septic tank can hold its own for quite a long time—especially when regular maintenance is performed, like a professional clean-out every three to five years. A well-maintained septic tank lasts around 20 to 40 years. Some types of septic systems can last even longer, but different variables can impact their performance.
Factors That Affect Your Septic Tank’s Life Span
Septic tank life spans can be affected by factors like materials, installation, and maintenance. Regular maintenance is an excellent place to start with your tank, but there are some additional things to consider.
Materials
Septic tanks are commonly constructed from polyethylene plastic, fiberglass-reinforced plastic, or precast concrete, but there are some steel tanks on the market, too. Concrete is a solid, rust-proof option that can last decades and sometimes even up to 100 years. Plastic tanks are also rust-proof but may get more easily damaged than concrete, especially in the event of a natural disaster or a water table rising up the bottom of the tank.
| Material | Average Life Span in Years |
|---|---|
| Steel | 15–20 |
| Plastic and fiberglass | 20–30 |
| Concrete | 40+ |
Ground and Installation
A professionally installed septic system will ensure everything is properly constructed, connected, and buried in the ground. Soil types also play a part in your system’s life span, depending on if you have non-acidic or highly acidic soil. Non-acidic soil is preferable since highly acidic soil can corrode and wear down steel, plastic, and cast-iron tanks.
Maintenance
Periodic inspections and professional maintenance can keep your septic system in good working order and potentially even add to its longevity. You'll want to have your tank and your entire system inspected and have pumps performed routinely by a plumber near you. Pumping frequency can vary depending on how many people live in your home and how much strain is on the disposal system.
Other maintenance activities recommended by the Environmental Protection Agency that can help protect the soil and groundwater around the system include inspecting and replacing the natural biomat (especially if your system is more than 25 to 35 years old) and replacing any pumps or controls every 10 to 20 years.
Signs Your Septic System Needs to Be Replaced
Sometimes, septic systems malfunction, and it’s rarely subtle when it happens. If you’re unsure of your septic system’s previous maintenance or you’re experiencing any of these signs, you’ll want to get in touch with a local septic tank company. These signs may include:
Persistent clogs: If clogs are frequent and other lines are pushing water back up through drains, you may have damage to your sewer line.
Gurgling pipes: Spontaneous and continuous (or non-routine) sounds from the pipes can also indicate a blocked sewer line.
Sulphuric or bad smells: Waste smells bad, and when the treatment system isn’t working properly or is backed up, the odors are likely to make their way onto your property in a very noticeable way.
Soggy landscaping: If it hasn't rained lately and you notice there’s a soft, boggy section of your lawn, the extra moisture could be coming up from an oversaturated drain field.
Cost to Maintain or Replace a Septic Tank
When it comes to septic system costs, maintenance is definitely preferable to a full replacement and is key to optimizing your septic tank's longevity. Maintenance typically costs around $300 to $600.
But in the event that your septic tank is reaching the end of its life, here are some averages that can help you ballpark the project costs. If just the tank needs to be replaced, it can run from $3,000 to $10,000. Other parts may also need to be replaced, and these range anywhere from $30 to $1,500. Replacing a drain field costs $7,000 on average.
Lacy Brunnette contributed to this piece.
Frequently Asked Questions
Since septic tanks are buried underground, they are not as susceptible to damage as other home components. However, floods and heavy rains can all cause overflow. Tree roots, while not a disaster, are a slow-growing and persistent nuisance that can disrupt the performance and longevity of different septic system components.
Septic tank fixes and sewer system repairs can add up quickly, especially in a case where a home is being sold “as is” and may have been sitting without care for some time. A sewer scope inspection can help you evaluate the potential damage so that you can get a project estimate and see if it’s worth your time and money to begin the necessary repairs. On average, a sewer line camera inspection costs $685.
Yes, some concrete septic tanks can last up to 100 years. However, your tank’s life span will depend on a few factors, including how well you take care of it and the soil conditions in your area. If you want to keep your tank working for as long as possible, make sure to follow the basics of septic tank maintenance, such as having your tank inspected and pumped every few years.
If your septic tank is full, you might notice sewage backing up into your drains or hear gurgling noises from your pipes, toilets, or sinks. In your yard, there might be flooding, patches of grass that seem particularly vibrant and healthy, or insects gathering near your drain field or septic tank lid.
It depends on the capacity of your septic tank, but to be safe, limit yourself to one or two loads of laundry per day with a septic system. If you need to wash multiple loads in a day, space them out so that your system has enough time to properly process the wastewater. Otherwise, you could end up with a clogged or flooded drain field.