Septic System Life Expectancy & the role of septic system maintenance

  • SEPTIC LIFE EXPECTANCY - CONTENTS: Life Expectancy of Septic Systems and Their Components. How long does a septic tank last? How long does a septic leach field or drainfield last? What is the life expectancy of septic system piping, D-boxes, septic pumps, and other septic system components
  • POST a QUESTION or READ FAQs about the typical life expectancy of septic system components
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Septic system life expectancy:

This document describes the typical life expectancy of septic systems and various common septic system components. The life expectancy of a septic tank depends largely on its materials, while the life of septic system piping depends largely on the risk of damage from vehicle traffic, clogging by roots, or flooding by groundwater.

The life expectancy of a drainfield varies widely by installation type (conventional soil absorption system versus a sand bed filter, for example), by soil conditions (clay or rock or sand), and importantly, by the frequency of maintenance and cleaning which has been performed on the septic system.

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Septic System Component Life Expectancy

Understanding the proper procedures for septic tank care, septic tank cleaning frequency, and other septic tank maintenance chores, will permit the owner of a home with an onsite septic system to maximize the life of the system and to assure that it is working properly.

How Quickly Does A Septic System Fail? How long will a septic tank, D-box, or absorption bed last?

Readers should see SEPTIC LIFE MAXIMIZING STEPS, and see Septic Tank Pumping Procedure for a detailed step by step photo-illustrated guide to find, pump and clean a septic tank. The life of the entire septic septic system depends on the following factors:

How Quickly Will the Septic System Fail if We Have One or More of the Problems Listed Above?

Septic systems (tank and absorption system, or onsite wastewater disposal systems) will not fail immediately if they are not pumped. However, an un-maintained septic tank is no longer protecting the soil absorption field from solids. Continued neglect shortens the drain field life and may result in system failure and even require complete replacement of the soil absorption field. In some cases, site limitations may make replacement of the absorption field impossible - at least impossible using a conventional drainfield design. Alternative designs are available to solve these problems.

So provided you've addressed these factors in septic system life, how long can you expect a septic system to last before costly repairs to the septic tank or septic drain field are required?

How Long do Individual Septic System Components like Tanks, Piping, D-Boxes, Filters or Pumps Last?

A steel septic tank will rust out on a schedule affected by soil acidity and tank steel quality and coating integrity. A steel septic tank more than 15 or 20 years old is likely to have already rusted to the point of having lost its baffles and perhaps having a rusted-out bottom - conditions that can be recognized during septic tank cleaning and inspection. A steel septic tank cover lasts until some fool drives over it or it rusts out.

A concrete septic tank can last 40 years to nearly indefinitely, though poor quality concrete or acidic ground water may result in deteriorated baffles or tank components.

A conventional septic drain field has a varying life as a function of the soil percolation rate, drainfield size, and usage level. I've seen a septic drainfield, a large one in good soil with a well maintained septic tank, last for more than 50 years. I've seen a conventional septic drainfield fail within 24 hours of first use on a new system when piping was poorly installed.

There is therefore a very wide range of life for this component. Experience of neighbors who have similar soils and similar systems can be helpful if you ask. In general, if I know nothing but that there is a conventional septic drainfield or a raised bed system and it's 20 years old, I consider its forward life not predictable and advise owners to budget for its replacement at any time.

The septic tank is only one part of an on-site wastewater system. It is designed to remove solids prior to the effluent entering the soil absorption field, provide for the filtration, digestion of a portion of those solids, and storage of the remaining solids. Taking care of the septic tank will, however, extend the life of the costly second half of the onsite wastewater treatment system - the absorption system, leach field, or drainfield.

Details about the life expectancy of a septic system

What to Do if you have just moved into a home with a septic system

If you've just moved into a home with a septic tank you may not know the size of the septic tank, its maintenance history, or even where the septic tank is. In this case, you should have the tank pumped and inspected. The company pumping the tank will tell you its size, age, and condition.


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