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Water Softeners

Water is often called the universal solvent, though people with hard water problems would hardly agree. Too bad water doesn’t come with instructions.

When it hits the ground, rain interacts with vegetation, top soil, and bedrock, dissolving whatever is soluble and finally ends up in our lakes, rivers, streams and ground water. Of the soluble minerals that end up suspended in the water calcium, magnesium and iron are three that can make our water “hard.”

Ion exchange explanation image

Hard water causes soaps and detergents to lose some effectiveness. The mineral salts react with soap to form an insoluble mix that can lead to coagulated curd and a film or scum. Soap in suspension does nothing to clean your clothing but just gives you something more to clean including bathtub rings, spots on dishes, etc.

Fear not homeowners, there is zeolite to the rescue! Zeolites are minerals that are microporous cage-like molecules. Theses cages are interconnected forming a framework with many cavities and channels. The zeolite pictured here is the main ingredient in a water softener and is also called resin. A typical water softener is a mechanical device that is plumbed into your home's water supply system. All water softeners use the same operating principle, trading minerals in a process called “ion exchange.” The zeolite/resin carries a negative charge and the offending minerals carry a positive charge. The positive charged mineral ions exchange places with the weaker positively charged sodium ions and are held fast in the zeolite until they themselves are knocked off during the recharge cycle. After recharging, the zeolite is cleaned of the bad minerals and reunited with its slightly positive friend the sodium ion and ready to attract more minerals in the water stream.

The essential part of a water softener is the mineral tank that holds the negatively charged resin/zeolite beads. Calcium, magnesium and sodium (the minerals that make your water hard) carry positive charges with sodium holding the weaker charge of the three.

Zeolite

Zeolite

As the water moves through the tank, the minerals will displace the weaker charged sodium ions and become entrapped in the zeolite. If all is working correctly, after the zeolite bed is completely saturated, the unit will recharge itself with a strong brine (salt) solution. The force and strength of the solution knocks the minerals off the beads and reseats the sodium ions back into the zeolite beads.

The recharging of the mineral tank is dependent on the type of softener you have and will activate on either a preset amount of time or amount of flow. The cycle of regeneration as shown above is four steps:

Water softeners cycle

  1. Backwash- this takes dirt and any accumulated debris out.
  2. Brining slow rinse – this is the step where the concentrated salt solution (brine) is slowing filled into the tank.
  3. Fast rinse- quickly rinses the resin bed.
  4. Brine tank refill - and back into service.

Soft Cycle Pic 1Soft Cycle Pic 2Soft Cycle Pic 3Soft Cycle Pic 4Soft Cycle Pic 5

Environmental Impact

The environmental costs of water softening systems are that they discharge water to drain that greatly increases salinity each time the water softener regenerates. The added salinity in the wastewater stream discharged to a sanitary sewer system has a negative impact on the environment. In numerous studies, this discharge is not been found harmful to septic systems with the exception of an apparent increase in corrosion in concrete tanks. Additionally, it has been found that the calcium and magnesium discharged in wastewater may even help improve soil percolation after passing through a septic system.

House and yard plants should not be watered with soft water. Generally, water with high sodium content can damage a plant's root systems.  Plants also need magnesium and calcium and softened  water removes those nutrients from water. 

Soft water may not be as healthy to drink as hard water for people that are on a low sodium diet. The taste of soft water may not be as pleasant as hard water.

    Considerations when purchasing a water softener

  • Have your water tested to determine the hardness and strength of other impurities.
  • Calculate how much softened water your household uses (remember that outside taps should not be included).
  • Buy the equipment that will meet your needs using your water test as your guide.
  • Take serviceability into account. For example a softener with a brine tank will need periodic cleaning.
  • Regeneration on demand models will use less salt/potassium chloride.
  • Consider if the additional sodium intake will be a health concern for your or your family.
  • Look at reputable guaranteed equipment that is certified by Underwriters Laboratories (UL) and National Sanitation Foundation, (NSF) or Agriculture Water Quality Alliance (AWQA)

 

Additional considerations and maintenance tips

If the water in your home contains levels of clear water iron, it is recommended that you use a salt pellet that contains an iron-removing additive. For information on identifying iron in your water see the table here.

If you have a high level of clear water iron, it may be beneficial to use a resin bed cleaner to remove any build up of iron residue in the resin bed. Use caution when using this type of cleaner and follow instructions carefully. Follow the manufactures recommendations for the frequency in which to use this product.

Potassium Chloride may be used as a substitute for salt in a water softener and maybe a good choice for people on restricted sodium diets.  This will make the unit regenerate more often because potassium chloride is not as efficient as salt. It is recommended that the consumer set the water hardness 20% higher when using potassium chloride instead of salt. Mixing salt and potassium chloride will have no adverse effects on the softener.

Set your water softener for the correct hardness level. The majority of water softeners have multiple hardness settings and need to be set for your specific level of harness.  Setting the softener for the proper hardness will save you money on salt, conserve on water use and lessen your impact ion the environment. Additional information on how to calculate your setting.

Magnetic conditioning

Permanent magnetic water conditioning devices have been marketed based on a variety of claims regarding their effect on water hardness. Tests conducted by Perdue University, Canadian Water Quality Association, and Consumer Reports found no significant benefit from these devices.

 

Water hardness is measured in grains per gallon (GPG) or milligrams per liter (mg/l)

(mg/l, equivalent to parts per million, or ppm).

Companies provided free water testing for hardness and testing kits are available.

Hardness Table

Water Classification
Hardness, mg/L
Hardness. Grains/Gal
Sodium Added  mg/L
Soft
0 to 49
0 to 2.9
0 to 22.5
Medium Hard
50 to 149
2.9 to 8.7
23 to 68.5
Hard
150 to 249
8.7 to 14.6
69 to 115
Very Hard
250 to 299
14.6 to 173
115 to 138
Extremely Hard
300 and up
17.5 and up
138 and up
mg/L = milligrams/Liter

 

A Map showing average hardnes of (a) surface water and (b) groundwater weighted against population served in major drainage areas.

Map A Map B

 

Reference / links
Performance Analysis of Permanent Magnet Type Water Treatment Devices
C. E. Gruber and D. D. Cadre of the South Dakota School of Mines and Technology, 1981

Qualitative Assessment of the Effectiveness of Permanent Magnetic Water Conditioning Devices.
J. E. Alleman of Purdue University's school of civil engineering. 1985

Consumer Reports February 1996, Consumer Reports September 1998

Softener Brines Do Not Harm Household Sewage Systems  Etzel, Dr. James E., Purdue University, West Lafayette, Ind., 1978.

The Results of Putting Brine Effluent into Septic Tank Drainage System,
Wood, Frank O., Salt Institute, Alexandria, Va., 1984.

Impact of Water Softeners on Septic Tanks Field Evaluation Study Final Report
Ontario Rural Wastewater Centre Collège d’Alfred – University of Guelph
Chris Kinsley, Anna Crolla, Doug Joy. July 15th, 2005

Iron Bacteria in Water Wells Maintenance Recommendations and Remediation Techniques
http://www.webs.uidaho.edu/gwemo
/reports/Iron_Bact_Remediation.pdf

Bacteria in Your Water
National Ground Water Association
www.NGWA.org www.wellowner.org
- www.ngwa.org/ASSETS/24B153A377A348EA8227FBCCBEC4DCC1/nov77.pdf