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Plumbing: Septic Systems


Septic systems are designed to separate liquids from solids, allowing the liquids to drain into the soil, where the earth’s natural filtering process treats the wastewater as it percolates through the gravel and soil. From the house, wastewater enters the septic tank, where solids drop to the bottom to create sludge, and grease and oils rise to the top to create scum. The wastewater between the two layers flows to a distribution box, which sends it out to a series of absorption, or leach, trenches. The wastewater is absorbed by the surrounding gravel and soil. The sludge on the tank bottom decomposes with the help of bacteria. Excess grease or other contaminants can destroy the bacterial action and, if allowed to flow into the leach field, can coat and clog the rock and soil and prevent absorption. A grease trap and careful maintenance can prevent this problem.

In a typical private septic system, waste is piped out of the house into a watertight holding tank, or septic tank, where bacteria breaks down the waste into solids, called sludge; liquid, called effluent; and scum. The sludge settles to the bottom of the tank, the scum rises to the top and the effluent flows into a distribution box, which channels it through perforated pipes to differ ent parts of a drainage field of loose gravel.

The proportions of sludge, effluent and scum must be carefully balanced for the tank to function properly. If particles of sediment get into the effluent and clog the drainage field, a health hazard results. Pumping removes the sludge and part of the scum to restore the proper balance. Consult your city or local septic-tank service about how often you should have your tank inspected and cleaned. To help with cleaning and inspection, locate and mark the caps and outlet covers of your system. If you don’t know where they are, refer to the septic system’s original design plan or check with your local building department.

Practicing water conservation is essential for you to have a long-lasting septic system. Large volumes of water, especially when delivered to the system over short periods, flush suspended, untreated particles into the drain field and clog it. Bathrooms account for 60 % of the water used in a typical home, so it’s the first place to start saving. Replace old toilets with new ones that use less water. Install water-saving showerheads and take shorter showers. Repair dripping faucets and shut off the tap when shaving or brushing your teeth. Water-saving clothes washers and dish washers can further save hundreds of gallons or liters per month.

Caution: Keep a tight lid on your septic tank. Most tank lids can be secured to deter curious children from dangerous exploration.

Figure 1 (right): Septic systems are designed to separate liquids from solids, allowing the liquids to drain into the soil, where the earth’s natural filtering process treats the wastewater as it percolates through the gravel and soil. From the house, wastewater enters the septic tank, where solids drop to the bottom to create sludge, and grease and oils rise to the top to create scum. The wastewater between the two layers flows to a distribution box, which sends it out to a series of absorption, or leach, trenches. The wastewater is absorbed by the surrounding gravel and soil. The sludge on the tank bottom decomposes with the help of bacteria. Excess grease or other contaminants can destroy the bacterial action and , if allowed to flow into the leach field, can coat and clog the rock and soil and prevent absorption. A grease trap and careful maintenance can prevent this problem.



Septic tanks should be inspected and pumped out every two or three years, depending on the size of the system and the number of people using it.

Maintaining a Septic System

Most septic systems are designed to last 20 or more years; however, if you carefully maintain your system following these rules, it can last indefinitely.

  • Have the tank cleaned every two or three years.
  • Stagger baths and wash loads to avoid overloading the system.
  • Don't pour paints, chemicals, drain cleaners or oils into drains or toilets.
  • Never dispose of grease, fat, coffee grounds, paper towels or facial tissues in sinks or toilets.
  • Be sparing in use of any cleaning product not labeled septic-safe, especially those with bleach or antibacterial agents.
  • Use a garbage disposer sparingly or not at all.
  • Direct runoff from gutters or drainage spouts away from the drainage field.
  • Don't park or drive over drainage fields.
  • Call for service if smelly water rises from the drainage field or if water backs up out of drains.
  • Don’t use commercial tank treatments -- they can liquefy sludge, allowing it to flow into drainage fields and clog leach lines.

Figure 2 (right): Septic tanks should be inspected and pumped out every two or three years, depending on the size of the system and the number of people using it.

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Recommended Reading

The Septic System Owner's Manual

The Septic System Owner's Manual

Book Description

by Lloyd Kahn, Blair Allen, Julie Jones, Peter Aschwanden

Topics include:

drainfield soil, meander tank, shallow drainfield, composting toilet systems, drainfield trench, drainfield failure, onsite systems, graywater systems, dosing siphon, seepage bed, septic tank effluent, effluent filter, outlet tee, scum layer, seepage pits, household wastewater, composting toilets, accumulated solids, effluent flows, high groundwater, septic system, pump chamber, sand filter, wastewater disposal, wastewater systems

Reviews:

GREAT ADVICE and PRACTICAL SUGGESTIONS: I live just 40 Kms outside a city of 3.5 million people but the 20 acre properties means that a sewered system would be cost prohibitive. So we have a septic tank system.

When you get one of these, there are few if any instructions so you learn by trial and messy error.

This is a great book for those new owners and users of these systems. It is a simple list of what to do and what to avoid.

I would highly recommend it to all septic system owners and users.

A "must" for all syptic system owners: The basics of septic systems, from underground systems and failures to what the owner can do to promote and maintain a healthy system, is revealed in an excellent guide essential for any who reside on a septic system. Rural residents receive a primer on not only the basics; but how to conduct period inspections and what to do when things go wrong. History also figures into the fine coverage.

Eureka! Finally a simple, straightforward explanation about a subject everyone should know about. In the Pacific low-lying atolls with very little land they wonder why flush toilets aren't suitable for them, and are being told composting, dry systems should be the way to go, but they don't understand why. This Pacific islander now understands why, thanks to this manual.

Fantastic! Very readable-entertaining despite the poo topic. I called author to compliment him.
It resulted in me upgrading my system and saving lots of money. Unique grapic arts/cartooney illustrations. Historically accurate.

Must Read - Before you troubleshoot or repair a septic system: My septic system indicated that it was in trouble about 8 months ago. I researched a lot of material (using various books and the internet). I can tell you from experience that I couldn't find one definative answer or method on how troubleshoot and /or repair a sick septic system or leach line(s).

However, the "Septic System Owner's Manual" by LLoyd Kahn, Blair Allen, and Jule Jones (copyright 2000) got me immediately in the right direction. In the end the book gave me enough information that allowed me to fix my problem myself. It took 7 months of hard work and negotiation with rock haulers, but the job got done. I personnally saved $3500.00 using the basic fundamentals presented in this guide.

In addition, if you don't know anything about how a septic system works or are courious, sections 1 and 2 are a must read. The information contained in the bibliography beginning with page 148 is also very illuminating. This information led me to 6 research papers written by various major universities on the use of private septic systems in the United States.

In summary, don't spend a dime until you study this guide.

Excellent non-technical information on Septic Systems: As a newbie to septic systems faced with having to build (or have built) a septic system, I checked out this guide along with a couple others from our local library. This was the only one I fully read, and I liked it so much I bought myself a copy.

I was first drawn to the book by the whimsical illustrations by Peter Aschwanden, but was hooked in by how accessible and informative the book was. We learned enough to ask intelligent questions of the contractor we eventually used to build our septic system. And, we learned a lot about the proper "care and feeding" of a septic system and now feel comfortable that we can treat ours in the proper manner to avoid septic troubles.

Highly recommended for the present or future septic system owner.

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Water Wells and Septic Systems Handbook

Water Wells and Septic Systems Handbook

Book Description

Packed with 200 illustrations!

A PRACTICAL, ONE-STEP RESOURCE FOR WORKING WITH WATER WELLS AND SEPTIC SYSTEMS.

Each year, thousands upon thousands of Americans install water wells and septic systems on their properties. But with a maze of codes governing their use—along with a host of design requirements that ensure their functionality—where can someone turn for comprehensive, one-stop guidance? Enter the Water Wells and Septic Systems Handbook from McGraw-Hill.

Written in language any property owner can understand—yet detailed enough for professionals and technical students—this easy-to-use volume delivers the latest techniques and code requirements for designing, building, rehabilitating, and maintaining private water wells and septic systems. Bolstered by a wealth of informative charts, tables, and illustrations, this guide delivers:
* Current construction, maintenance, and repair methods
* New International Private Sewage Disposal Code
* Up-to-date standards from the American Water Works Association
* And much, much more!

So, no matter if you’re a plumber, a driller, or a utility company professional, Water Wells and Septic Systems Handbook is the one resource you need to ensure your next job’s success!

About the Author
R. Dodge Woodson (Fort Fairfield, ME) has over 20 years' experience as a home builder, contractor, master plumber, and real estate broker. He is the author of many McGraw-Hill books, including Be A Successful Building Contractor 2/e, and National Plumbing Codes Handbook 2/e.

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Last modified: Friday, 2007-11-02 22:02 PST