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Septic System Maintenance - Septic System Life Expectancy InspectAPedia®  -     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

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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.

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.

Also see Septic Tank Pumping Procedure Detailed step by step photo-illustrated guide to find, pump and clean a septic tank. © 2008-1978 Daniel Friedman, All Rights Reserved. Citation of this article by reference to this website and brief quotation for the sole purpose of review are permitted.

Use of this information at other websites, in books or pamphlets for sale is reserved to the author. Technical reviewers are invited and are listed at "References."

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Septic System Component Life Expectancy

How Quickly Does A Septic System Fail?

The life of a septic system depends on the following factors:

• Septic Tank Pumping Frequency: providing you are starting with a functional and reasonably-designed septic system, the most significant step you can take to extend the septic system life is to have the septic tank cleaned or "pumped" on schedule. See TANK PUMPING SCHEDULE for a table that determines how often a particular septic tank needs this service.
• How the Septic System is Used: including the wastewater usage level and what materials are flushed down the septic system drains. Conserving water reduces the load on the absorption field. Avoiding flushing chemicals or items that don't biodegrade reduces the solid build-up rate in the septic tank. See "Don't Flush these things into a septic system" for a list of what's ok and what's not ok to put into septic tanks and building drains.
• Soil Conditions such as the soil percolation rate and the amount and level of ground water or surface water that affect the soil absorption area or drain field.
• Septic Tank Materials: a steel septic tank rusts away, first losing its baffles (which lead to drain field clogging) and eventually rusting at its bottom or sides. The rate of rust depends on the soil conditions and soil acidity and other factors. A concrete septic tank can have a very long life, in excess of 40 years, except for cases of poorly-mixed concrete or possibly acidic soils which may reduce that span. Plastic or fiberglass septic tanks can expect to have a similar life unless they are mechanically damaged.
• Life of Special Components such as effluent pumps or septic grinder pumps, septic filters, septic media, and sand bed filter systems often determines the need for repair of alternate-design septic systems that use these components.
• Nearby trees or plants whose roots invade system components.

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?

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.

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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SEPTIC SYSTEMS HOME
SEPTIC SYSTEMS ONLINE BOOK
SEPTIC SYSTEM DESIGN BASICS
TANK PUMPING SCHEDULE
  TANK PUMPING FREQUENCY TABLE
  WHY DOES A TANK NEED PUMPING?
  EFFLUENT RETENTION TIME
SEPTIC TANK PUMPING PROCEDURE
SEPTIC TANK INSPECTION PROCEDURE
MEASURE SCUM & SLUDGE
CLEANING SEPTIC TANKS
WHEN NOT TO PUMP A SEPTIC TANK
SEPTIC PUMPING CONCLUSIONS
SEPTIC LIFE EXPECTANCY
SEPTIC FIELD INSPECTION
SEPTIC TREATMENTS
SEPTIC TANK SAFETY
SEPTIC VIDEOS

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06
• Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. 11/29/06

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• The Septic System Information Website home page for this topic
• Septic Systems Inspection, Testing, & Maintenance- online textbook. Detailed how to inspect, maintain, repair information


• Cesspool Life - determining the age of a cesspool
• The Home Buyer's Guide to Septic Systems
• SEPTIC TANK PUMPING SCHEDULE When, Why, How to pump the septic tank
• Septic Tank Pumping Procedure step by step photo guideline of how to pump and clean a septic tank - septic tank care
• Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location
• Home & Outdoor Living Water Requirements
• Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
• Septic System Design Basics: Choosing Septic Tank Size, Absorption System Size
• Table of Required Septic & Well Clearances: Distances Between Septic System & Wells, Streams, Trees, etc.
• Ten Steps to Keeping a Septic System Working, suggestions from the U.S. EPA, edits and additions by DJF
• Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
  
• Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
• Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
• Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
• Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)
• ...

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