How Water Softeners Work - operation, maintenance, adjustment, and water softener effect on drinking water and on septic systems. InspectAPedia® -
How water softeners work, methods to remove minerals from home water supply
Managing salt in drinking water
Questions & answers about how water conditioners and water softeners actually work.
Here we explain how water softeners and similar water conditioners work, types of water softeners, and the basics of what water softener controls are present and what they do.
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\ Also see SOFTENER ADJUSTMENT & CONTROLS where we provide details about water softener setting and salt dose adjustments.
HOW Water SOFTENERS WORK - Water Softener Operation: How Do Ion Exchange Water Softeners Work
Conventional ion-exchange water softeners used to remove minerals from "hard" water in buildings usually use salt in an ion-exchange process,
swapping in sodium ions (salt) and causing calcium and magnesium to precipitate out of the building water supply (and to collect
in the water softener). Hard water is generally taken to mean water containing minerals over 121 mc (micrograms) per liter of water, or over 7 grains of hardness per gallon.
Resin inside the water softener contains salt molecules which are brought into contact with
building water as it passes through the softener. The "resin" is made of tiny plastic beads of zeolite which are coated with salt or potassium ions. (Ions are molecules that have an electrical charge.)
As hard water which is to be treated flows through the treatment tank containing the salt-coated zeolite resin beads, salt molecules (NaCl) on the bead surface are "swapped" into the water displacing other mineral molecules that we're trying to remove from the water, such as Calcium (Ca) or Magnesium (Mg) that clog up pipes and create other problems. The Ca or Mg ions stick to the resin beads where they have replaced the NaCL.
In sum, during that contact time as your building water passes through salty resin inside the treatment tank, the ion-exchange occurs to soften the water.
Water Softener Recharge or Regeneration Cycle: Periodically the water softener needs to recharge itself, a step which is controlled either manually by the
homeowner or run automatically by a timer built into the water softener. Usually these steps involve pumping water backwards through the water softener and to a building drain, followed by
dissolving salt tablets or crystals in a nearby holding tank and pumping the new salty water into the softener.
During a water softener regeneration or recharge cycle two things happen:
Water is first pumped into the brine tank (the larger of the two water softener tanks in traditional installations) where it dissolves salt that is in the tank (you put it there) in the form of salt crystals or pellets.
The salty backwash water is next pumped out of the brine tank and back through the water softener treatment tank (the smaller of the two water softener tanks) where it does two more things:
The water softener backwash - regeneration cycle washes out the precipitated
calcium and magnesium which have stuck to the zeolite bead surface - thus having been removed from the water supply,
The salty backwash water passing through the water softener treatment tank it also re-charges the salt in its ion exchanger - salt molecules stick to the surface of the zeolite resin beads.
The salty water passing back through the treatment tank has given up some of its salt to regenerate the resin beads there and it has picked up the un-wanted calcium and magnesium that were previously removed from the building water as it passed through the same tank earlier. The water used during the regeneration cycle gallons is discharged through a drain tube into an approved destination like a drywell.
How often a water softener needs to backwash and recharge itself depends on two factors: how much water is used in the building and
how hard the water is.
How much salt a water softener uses at its backwash cycle depends on the hardness of the water being processed.
Water softeners address these two variables and is regenerated or "recharged" by these means:
Offsite or "swap-in" water softeners: a water softener treatment tank is brought into the home and installed using quick-disconnect plumbing fittings. On a regular schedule a water treatment company comes by and swaps out the old treatment tank, installing a new one that has been regenerated or cleaned at their facility. This type of water softener does not use any electricity and has no controls other than a bypass valve. (We had one in our first home, maintained by Culligan™).
Manual water softeners: manual backwash/regeneration cycle of the water softener initiated by the owner who is supposed
to notice that the water feels "hard" (can't get a lather in the shower) or as part of maintenance say when the water softener has been shut down for a week or more
Automatic regular periodic backwash/regeneration in the water softener accomplished by a clock timer
attached to the water softener
Automatic "as needed" backwash/regeneration in the water softener, controlled by a sensor in the (more costly) water softener monitors either water hardness (water hardness sensor) at the softener outlet pipe or the total volume of water used (water metering) and
backwashes (regenerates) when needed.
Twin-tank water softeners are available for installations (such as commercial) where 24-hour availability of soft water is needed. - IBC.
The water softener installer sets up the water softener control to specify:
How often the automatic periodic regeneration cycle should occur, such as once a week, once every other day, etc.
What time of day the regeneration cycle should occur - typically at 2AM when people are unlikely to be using water
How much water should be used during the water softener backwash - regeneration cycle - this is specified by adjusting the time-duration of the backwash cycle. Factory default is typically 10 minutes of backwash time. The cycle may be adjustable to a time ranging between 5 minutes and 30 minutes as needed. The number of gallons of water used during the water softener backwash cycle varies depending on the water pressure and flow rate in the building water supply piping.
A rough guess would be a typical volume of about 30 gallons of water (3 gpm for 10 minutes) but could be as little as 10 gallons or as much as perhaps 150 gallons (5 gpm for 30 minutes). If your water softener is running longer than 30 minutes during a backwash cycle it may not be working properly.
How much salt should be used during the water softener regeneration cycle
Some experts
suspect that many homeowners use more salt and more frequent backwashing than the water usage and hardness require.
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North Dakota Standards for Water Softeners, North Dakota General Authority Law, Chapter 62-04-08, Water Softener Units http://www.legis.nd.gov/information/acdata/pdf/62-04-08.pdf. "The objective of this chapter is to provide a standard of quality, capacity,
and performance for water softener units. Water softener performance
is to be based upon referee tests procedures described in section
62-04-08-09."
Culligan Mark 10 Water Softener 1994-1998 Installation and Operating Instructions (covering models manufactured after 1995) (1-96) 01881948.pdf available from www.culligan.com
Water Softeners, CMHC, Canadian Mortgage and Housing Corporation, cmhc-schl.gc.ca/en/co/maho/wawa/wawa_005.cfm - October 2008. Canada Mortgage and Housing Corporation acknowledges the contribution of Health Canada to the development of this document. For further questions regarding water treatment and water quality, contact Health Canada at watereau@hc-sc.gc.ca or call 613-957-2991 or 1-866-225-0709.
"Commercial Water Softener Installation and Operating Instructions", IBC Filtration & Water Treatment Products (Australia) for commercial, industrial and residential application www.ibcwater.com.au (07) 3219 2233
"Non electric water softener,
Installation and Operating Instructions", IBC Filtration & Water Treatment Products (Australia), op.cit.
Watts Industries of North Andover, Mass., provides its ZRO-4 under counter system intended to target the independent water dealer market.
"Water Softener Twin Tank Installation and Operating Instructions", IBC Filtration & Water Treatment Products (Australia), op.cit.
Our Water Hardness Table used at originated with but was edited and added to from http://www.bestfish.com/tips/110598.html and also from http://www.water-research.net/hardness.htm
Thanks to reader Walter Schwartz
for discussing water softener salt dose settings - September 2010
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, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Onsite Wastewater Disposal Books
Onsite Wastewater Disposal, R. J. Perkins;
Quoting from Amazon: This practical book, co-published with the National Environmental Health Association,
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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.
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
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
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.
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* Current construction, maintenance, and repair methods
* New International Private Sewage Disposal Code
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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
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