LARGER SKETCH of a small diameter pressure dosing system - EPA

Using Pressure Dosing as a Component of Alternative Septic Systems for Difficult Sites

Design for pressure dosing septic systems
- Gravity dosing septic system designs, Manifold dosing septic system designs and applications, Rigid pipe dosing septic system designs and applications, Pressure Drip Effluent Dosing Systems - Dripline septic systems for septic effluent disposal
PRESSURE DOSING SYSTEMS
Questions & answers about pressure dosing septic system designs
References

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This document discusses types of effluent pressure dosing septic systems, including gravity dosing, pressure manifold dosing, rigid pipe pressure dosing, and dripline effluent dosing systems for septic system effluent final treatment and disposal. 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 review by industry experts has been performed and is ongoing - reviewers welcomed and are listed at References.

Readers interested in septic effluent dosing systems should also see GRAVITY/SIPHON DOSING SYSTEMS.

Pressure Dosing Septic System Designs

How and When Septic Effluent is Moved Through a Septic System - Methods For Septic Effluent Distribution Using Gravity Systems

Our sketch (left, edited courtesy USDA) shows a generic septic effluent dosing system, combining a septic tank, a dosing tank, a diverter valve,and two septic efflent dispersal loops through a soil absorption field.

Septic effluent is distributed to a system final treatment and disposal using either gravity methods (which depend on terrain slope - see GRAVITY/SIPHON DOSING SYSTEMS) or pressure methods - PRESSURE DOSING SYSTEMS (which use a pump to move effluent to its destination treatment and disposal area). Effluent may be distributed for final soil absorption by several methods listed here:

Single Effluent Line: A 4" perforated PVC pipe receives effluent by gravity from the septic tank. The pipe is buried in a gravel trench and may be run in a straight line or a loop.
Distibution Box/Network of Lines A distribution box receives effluent by gravity from the septic tank and routes it to a network of perforated pipes. The network is made of multiple independent trenches which maybe on a flat or sloped site.
Serial relief line: multiple, serially connected trenches are built on a sloping site and used serially.
Drop box: multiple independent trenches are built on a sloping site, connected from drop boxes.

The purpose of septic effluent "dosing" systems is to place septic effluent in the absorption system or drainfield at intervals rather than continuously. In effect, the effluent dosing chamber forms a "buffer" which receives and stores septic effluent flowing (or being pumped) out of the septic tank until a desired dosing quantity is reached. Then the effluent is dispersed to the absorption system in one "dose." By distributing effluent at intervals rather than on a more nearly continuous or irregular basis the absorption system can "rest" between cycles, extending its life and possibly increasing its ultimate effluent treatment and disposal capability. Not only does the rest interval permit the absorption system more time to dispose of its effluent, also the exposure of the system to air between doses can reduce the rate of clogging of the drainfield.

Methods For Controlling Septic Effluent Distribution Using Pressure Dosing Systems

The Pressure Dosing Controls Shown Below include a Pressure Dosing distribution manifold (below left) and a pressure dosing distributing control valve. Images courtesy Washington State DEHS.

Pressure Dosing Mainfild - DEHS Washington State

Pressure Dosing Distributing Valve - DEHS Washington State

Each septic effluent dosing system has its particular operating characteristics, so one type may be more suitable than others to a particular site. These types of pressure dosing septic systems are discussed here:

Pressure Dosing Methods permit effluent to be dispersed over the entire absorption field more uniformly than with gravity dosing systems, making maximum use of the absorption system capacity and avoiding the problem of local area or point overloading in the absorption field.

Pressure manifold: multiple independent trenches on sloped sites or multiple independent trenches receive effluent from a larger manifold pipe which is fed by an effluent pump from a pumping chamber.
Rigid Pipe Pressure Network: multiple independent trenches at the same elevation receive effluent from an effluent pump and pumping chamber.
Dripline Pressure Dosing Network: multiple independent pressure drip trenches on flat or sloping sites receive effluent from a pump and pumping chamber at low pressure (potentially even by gravity) where effluent is fed through small pipe openings permitting it to drip at a slow, controlled rate, into the trench and soils.

Controlled vs Uncontrolled Effluent Flow Control When Septic Effluent is Moved Through a Septic System

Wastewater effluent is distributed for final treatment over time either by uncontrolled, or controlled methods.

Uncontrolled septic effluent flow: A conventional gravity septic system and drainfield is "uncontrolled". When waste enters the septic tank, it forces the same volume of effluent out of the tank and into the leach field. Some experts call this a continuous or trickling septic system. Conventional septic tank and drainfields use this approach. The timing of effluent movement or "trickle" into the absorption field is based simply on when people are using the building plumbing and thus based simply on when wastewater flows out of the building into the septic tank.

Controlled septic effluent flow: in controlled systems effluent is sent to the final treatment and disposal system such as an absorption field under either mechanical control such as a tipping or siphon system or under pump control, such as by use of a dosing system which makes use of a gravity dosing method or a pressure dosing method such as septic effluent pressure manifold, rigid pipe distribution, or a septic effluent drip network.

In some large wastewater treatment systems with a significant if not uniformly continuous inflow, outflow of the system may be continuous in some designs. But many system use an intermittent effluent dosing method which operates by a pump controlled perhaps by a float in an effluent receiving chamber, or by a siphoning or tipping bucket mechanical system (gravity systems).

Pressure Distribution and Pressure Dosing Septic System Design Specifications

Pressure-dosed Drainfield Septic Systems use a separate effluent pumping chamber and an effluent pump such as the system in this sketch. The effluent pumping station is located downstream from the septic tank and is used to move septic effluent into a pressure-fed network of distribution pipes. In some designs the effluent is pumped to move it up to the absorption field where it then moves by gravity. Other systems pressurize the entire piping network.

Pressure dosing is used in a variety of disposal field designs including mounds and sand beds, and have the advantage of being able to distribute effluent uniformly throughout the absorption system, and the disadvantage of added system cost and complexity, along with the requirement for electricity for system operation.

An alternative but possibly less long-term reliable version of a drainfield dosing system that does not require electricity is the siphon system. The sketch shows a generic pumping station of the type used with many pressure dosing systems, source US EPA and Purdue University.

Source for the following is New York State regulations on wastewater treatment and design for individual household septic systems (Note b below) and from the U.S. EPA Wastewater Manual.

(1) These methods permit the rapid distribution of effluent throughout the absorption system followed by a rest period during which no effluent enters the system. The maximum length of absorption lines used in conjunction with these methods shall be 100 feet.

(i) Pressure distribution utilizes a sewage effluent pump to move the effluent through the pipe network and into the soil. The volume discharged in each cycle will exceed the volume available in the pipe network and will be discharged from the pipe under pressure.

(ii) Dosing involves the use of a pump or siphon for pressure dosing septic systems to move the effluent into the pipe network. Discharge from the pipe is by gravity. The volume of effluent in each dose should be 75% to 85% of the volume available in the pipe network.

(2) Dosing or pressure distribution is recommended for all septic systems as it promotes better treatment of wastewater and system longevity.

(3) In absorption fields, single pressure dosing units are required when the total trench length exceeds 500 feet. Alternate dosing units are required when the length exceeds 1,000 feet.

(4) The use of manually operated siphons or pumps for pressure dosing septic systems is not acceptable.

(5) Pipe used in pressure dosing septic systems distribution shall have a minimum diameter of 1.5 inches and a maximum diameter of three inches. Pipe for siphon dosing is sized to conform with the volume of the dose and can range from three to six inches in diameter based upon the volume of each dose. The ends of all pipes shall be capped.

(6) Only pumps for pressure dosing septic systems designated by the manufacturer for use as sewage effluent pumps shall be used.

(7) Pump chambers for pressure dosing septic systems shall be equipped with an alarm to indicate malfunction. Siphon dosing systems normally include an overflow to the distribution laterals. Pressure distribution systems shall not be equipped with an overflow.

(8) Pump chambers for pressure dosing septic systems shall be sized to provide a minimum of one day's design flow storage above the alarm level. Siphon chambers shall have a minimum total storage of one day's design flow below the overflow pipe.

Footnote (b): The preceding example septic pressure dosing system design and descriptive data for septic effluent pressure distribution and pressure dosing systems is from Appendix 75-A to Public Health Law, 201(1)(1) New York State Wastewater Treatment Standards - Individual Household Septic Systems, Wastewater Treatment Design and Regulation Section, specifically chapter 75-A.7 Distribution lines, distribution boxes, gravity flow, pressure distribution, dosing, siphons

Manifold Pressure Dosing Effluent Dispersal Systems

This sketch shows a closeup of the effluent distribution manifold. The effluent pump moves effluent from the dosing chamber to this manifold under pressure. Pressurized septic effluent leaves the manifold through the small diameter black tubes or "distribution laterals".

Notice that each lateral has an individual control valve permitting the user to balance flow or even to manually alternate which distribution laterals are to be in use and which are to be left at rest.

The enlargers shown at the end of each distribution lateral permit connection of the lateral to a 4" PVC perforated pipe buried in the absorption system.

We'd infer that the effluent dispersal within the 4" pipe is by gravity not by pressure as with the next system discussed below. [Photo, U.S. EPA. Click the sketch to see a larger image of this rigid pipe pressure dosing septic effluent system example.]

Rigid Pipe Pressure Dosing Effluent Dispersal Systems

This sketch shows a septic tank, the pumping chamber, also called a "dosing chamber" which contains the effluent pump, and the network of rigid pipe used to distribute effluent into the soil absorption system.

This design might be used with sand bed systems or mound systems as we discuss in this document. Note that the designer specified that a distribution line cleanout was to be provided at the end of each line.

This rigid pipe pressure dosing sketch appears also at the top of this page and in the EPA's Wastewater Manual. [Photo, U.S. EPA. Click the sketch to see a larger image of this rigid pipe pressure dosing septic effluent system example.]

Pressure Drip Dosing Effluent Dispersal Systems - Drip Line Septic Systems

This EPA sketch shown a basic effluent drip line system layout. Effluent flows from the septic treatment tank to a pumping chamber where an effluent pump moves the effluent to a control chamber. The control chamber feeds effluent to the drip lines.

A field flush or back-flush line is connected from the control chamber back to the tank to return any settled sludge or debris to the system.

The air/vacuum release valve is installed at the very end of the drip line to assure that effluent can flow through the line to its end. [Sketch, U.S. EPA adapted from American Manufacturing - a supplier of this equipment.

See our link to our listing of product sources below. Click the image to see a larger version of this drip line septic effluent dispersal system example.]

This photo shows the pressure manifold (white pipe) and flexible low pressure drip dispersal system lines (black tubing) to be used for septic effluent treatment and disposal.

As the photo caption indicates, the trench has not been filled. These components will be covered, not left exposed.

The smaller diameter black lines are the drip lines which you'll notice are buried close to the ground surface. Probably a warm climate design. [Photo, U.S. EPA, who obtained it from Ayres Associates.

Click the photo to see a larger image of this drip dispersal system example.]

Pressure Dosing Septic System Products and Suppliers

Please see ALTERNATIVE SEPTIC PRODUCTS and also review the suppliers listed at ATU Suppliers

Frequently Asked Questions (FAQs)

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf.

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

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd

Inspecting Septic Systems: Online Book, Inspection, Test, Diagnosis, Repair, & Maintenance: our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.

Advanced Onsite Wastewater Systems Technologies, Anish R. Jantrania, Mark A. Gross. Anish Jantrania, Ph.D., P.E., M.B.A., is a Consulting Engineer, in Mechanicsville VA, 804-550-0389 (2006). Outstanding technical reference especially on alternative septic system design alternatives. Written for designers and engineers, this book is not at all easy going for homeowners but is a text I recommend for professionals--DF.
Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP; Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP; Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.

Design Manuals for Septic Systems

US EPA Onsite Wastewater Treatment Systems Manual [online copy, free] Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm Onsite wastewater treatment and disposal systems, Richard J Otis, published by the US EPA. Although it's more than 20 years old, this book remains a useful reference for septic system designers. U.S. Environmental Protection Agency, Office of Water Program Operations; Office of Research and Development, Municipal Environmental Research Laboratory; (1980)
Eco John® Innovative Toilet Solutions, Global Inventive Industries, Fountain Valley CA, PDF, product brochure
"International Private Sewage Disposal Code," 1995, BOCA-708-799-2300, ICBO-310-699-0541, SBCCI 205-591-1853, available from those code associations.
"Manual of Policy, Procedures, and Guidelines for Onsite Sewage Systems," Ontario Reg. 374/81, Part VII of the Environmental Protection Act (Canada), ISBN 0-7743-7303-2, Ministry of the Environment,135 St. Clair Ave. West, Toronto Ontario M4V 1P5 Canada $24. CDN.
Manual of Septic Tank Practice, US Public Health Service's 1959.

Onsite Wastewater Disposal Books

Onsite Wastewater Disposal, R. J. Perkins; Quoting from Amazon: This practical book, co-published with the National Environmental Health Association, describes the step-by-step procedures needed to avoid common pitfalls in septic system technology. Valuable in matching the septic system to the site-specific conditions, this useful book will help you install a reliable system in both suitable and difficult environments. Septic tank installers, planners, state and local regulators, civil and sanitary engineers, consulting engineers, architects, homeowners, academics, and land developers will find this publication valuable.
Onsite Wastewater Treatment Systems, Bennette D. Burks, Mary Margaret Minnis, Hogarth House 1994 - one of the best septic system books around, suffering a bit from small fonts and a weak index. (DF volunteers to serve as indexer if Burks/Minnis re-publish this very useful volume.)
While it contains some material more technical than needed by homeowners, Burks/Minnis book on onsite wastewater treatment systems a very useful reference for both property owners and septic system designers. We refer to it often. While Minnis says the best place to buy this book is at Amazon (our link at left), you can also see this book at Minnis' website at http://web page .pace.edu/MMinnisbook
Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf
Soil Percolation Tests soil perc testing guide and instructions
Percolation Testing Manual, CNMI Division of Environmental Quality, PO Box 501304, Saipan, MP 96950
Planting Over Septic System Component", Daniel Friedman (author/editor, InspectAPedia.com), The Innovator, Winter/Spring 2008, BCOSSA, British Columbia OnSite Sewage Association, 201-3542 Blansard St., Victoria BC V8X 1W3 Canada
Save the Septic System - Do Not Flush These Items Down the Toilet, Daniel Friedman, InspectAPedia.com - PDF document, printable
SEPTIC STANDARDS
SEPTIC MAGAZINES
Septic System Owner's Manual, Lloyd Kahn, Blair Allen, Julie Jones, Shelter Publications, 2000 $14.95 U.S. - easy to understand, well illustrated, one of the best practical references around on septic design basics including some advanced systems; a little short on safety and maintenance. Both new and used (low priced copies are available, and we think the authors are working on an updated edition--DF. Quoting from one of several Amazon reviews: 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.
Test Pit Preparation for Onsite Sewage Evaluations, State of Oregon Department of Environmental Quality, Portland OR, 800 452-4011. PDF document. We recommend this excellent document that offers detail about soil perc tests, deep hole tests, safety, and septic design. Readers should also see Soil Percolation Tests and for testing an existing septic system, also see Dye Tests
Grass is Always Greener Over the Septic Tank, Bombeck, Erma: $ 5.99; FAWCETT; MM; This septic system classic whose title helps avoid intimidating readers new to septic systems, is available new or used at very low prices. It's more entertainment than a serious "how to" book on septic systems design, maintenance, or repair. Not recommended -- DF.
US EPA Onsite Wastewater Treatment Systems Manual Top Reference: US EPA's Design Manual for Onsite Wastewater Treatment and Disposal, 1980, available from the US EPA, the US GPO Superintendent of Documents (Pueblo CO), and from the National Small Flows Clearinghouse. Original source http://www.epa.gov/ORD/NRMRL/Pubs/625R00008/625R00008.htm
Water Wells and Septic Systems Handbook, R. Dodge Woodson. This book is in the upper price range, but is worth the cost for serious septic installers and designers. Quoting Amazon: 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 book delivers:
* Current construction, maintenance, and repair methods
* New International Private Sewage Disposal Code
* Up-to-date standards from the American Water Works Association
Wells and Septic Systems, Alth, Max and Charlet, Rev. by S. Blackwell Duncan, $ 18.95; Tab Books 1992. We have found this text very useful for conventional well and septic systems design and maintenance --DF. Quoting an Amazon description:Here's all the information you need to build a well or septic system yourself - and save a lot of time, money, and frustration. S. Blackwell Duncan has thoroughly revised and updated this second edition of Wells and Septic Systems to conform to current codes and requirements. He also has expanded this national bestseller to include new material on well and septic installation, water storage and distribution, water treatment, ecological considerations, and septic systems for problem building sites.
The NSFC Products List has an excellent list of design manuals/modules available from their website or by telephone 800-624-8301
Submissions welcome. send us a suggested document link or request an exchange of website links
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