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The presence of calcium (Ca) and/or magnesium (Mg) in water results in that water being termed “hard.” These mineral ions in the water react with heat, metallic plumbing, and chemical agents such as detergents to reduce the cleaning effectiveness of laundry, dish washing, and bathing.
Table I. Classification for water hardness (Hardness as CaCo) Classification Mg/L or PPM GPG
Soft 0-60 0-3.5
Moderate 61-120 3.5-7
Hard 121-180 7-10.5
Very Hard > 180 > 10.5
The calcium and magnesium ions typically are present in combination with sulfate, chloride, carbonate, and bicarbonate. These minerals generally are measured in either parts per million (ppm), or as milligrams per liter (mg/l).
The water conditioning industry often expresses water hardness in grains of hardness per gallon of water (gpg). The American Society of Agricultural Engineers has classified water hardness as indicated in Table I.
Hardness can be tested by water testing laboratories, some city-county health departments, and some water treatment equipment dealers. Most public water systems will be able to tell you the hardness of the water they deliver.
There are three main reasons for removing water hardness minerals before use. The minerals:
form soap curds that are difficult to clean,
deposit scale that clogs plumbing and fixtures,
build up scale in water-using appliances such as water heaters, require additional energy costs, and reduce equipment efficiency.
How Can Water Be Softened?
Hard water can be softened using ion-exchange water softeners, or using commercial water-softening chemicals in the laundry water. For most situations with water in hard and very hard classifications, an ion-exchange water softener is the desired alternative.
How Does Water Softener Equipment Work?
According to the Water Quality Research Council, all recognized home water softening equipment now on the market uses ion exchange processes to remove the hardness minerals from the water.
The hard water passes through a tank containing a high capacity ion exchange resin, usually sulfonated polystyrene beads which are microporous. The beads are supersaturated with sodium to cover both their exterior and interior surfaces.
As the water passes through the bed of softening materials there is an ion exchange. Calcium and magnesium ions attach to the resin beads while the sodium on the resin is released into the water. Figure 1 illustrates the softening process.
Figure 1. The water softening process.
Ion-exchange beads are extremely durable, but after softening a large quantity of hard water the beads become saturated with calcium and magnesium ions. When this occurs, the softener must be regenerated or recharged. This is done by flushing the ion exchange resin with a salt brine solution to replenish the resin with sodium ions.
Frequency of regeneration depends upon the hardness of the water, the amount of water used, the size of the unit, and the capacity of resins to remove hardness. Sixty to 75 minutes are required for the brine to pass through the unit and flush the tank before soft water is again available.
Mechanical water softeners are classified into the following types:
Manual — All manual units require the operator to initiate some or all of the steps in the softener operation. The most basic unit requires the operator to initiate all functions: backwash, brining, rinsing, and return to service.
Semi-automatic — The more complex semiautomatic units require the operator to initiate only the regeneration cycle. All necessary steps of regeneration and return to service then are handled by the softener controls.
Automatic — The fully automatic softener usually is equipped with a timer that automatically initiates the regeneration cycle and every step in the process. The regeneration of the unit usually is done during periods of low water usage, such as between midnight and 4 a.m.
Demand initiated regeneration — With a demand initiated regeneration unit, all operations are initiated and performed automatically in response to the demand for treated water. The need for regeneration is determined by measuring gallons of water used, or by measuring the change in the electrical conductivity of the resin bed, or by sensing a change in water hardness.
Off-site regeneration — In addition, rental units are available where the resin tank is exchanged in the home and then recharged at a central location. The basic installation of a water softener is illustrated in Figure 2.
Figure 2. The typical installation of a water softener.
What Are the Maintenance Requirements of Water Softeners?
A softener should be kept regenerated at all times to avoid hard water flowing into the pipes and water-using appliances. As a minimum guideline, regenerate the unit every two weeks.
The brine tank requires periodic cleaning. The frequency needed depends on the type and amount of salt used and the characteristics of the water being treated. Inspect the brine tank at least once a year for build-up of insoluble materials. Check and clean the brine valve and float assembly, if used.
The presence of excess iron, iron bacteria, or hydrogen sulfide quickly can inhibit the effectiveness of a water softening unit. In these cases installation of the proper pre-softening treatment equipment is important.
If your softener has a manual or semiautomatic back washing system, continue the back washing operation until the water runs clear. If backwash time is adjustable on a fully automatic unit, check to be sure the timer provides for sufficient back washing to produce clear water in the drain. If the water is still dirty, reset the timer for longer back washing.
Adequate back washing is essential to keep the bed of the unit clean for adequate regeneration.
What are the Differences in the Types of Softener Salt?
Softener salt can be compared with gasoline in a car. Manufacturers design their softeners for operation with specific types of salt, so it is good practice to use the recommended type. Common types of salt include compressed salt, block salt, and rock salt.
Compressed salt is produced by an evaporation process and contains less than .01 percent impurities. For household water softener use the evaporated salt is compressed into small particles referred to as pellets, nuggets, gems, pearls, zeo-tabs, and beads or buttons. These are sized according to the softener manufacturer’s specifications.
Salt blocks used in water softener brine tanks are the same general size, shape and weight (50 pounds) as those used for livestock feeding. However, the salt blocks used for animal nutrition generally contain binders or additives incompatible with water softener units.
Use block salt only in those units specifically designed for this form of salt. Make certain you use those made from high-grade evaporated salt without binders or additives.
Rock salt is a natural product that may have high levels of soluble or insoluble impurities. If the soluble impurities are salts of calcium or magnesium, they can significantly reduce the effectiveness of the chemical regeneration process. Insoluble impurities can collect in the brine tank or softener bed. This increases pressure drop, plugs valves, and requires more maintenance than usual. When using rock salt, always select those averaging less than one percent impurities.
Additives may be included with the salt to keep the softener bed from being clogged with iron. Selecting this specially formulated salt may be desirable when the water supply is high in iron.
Is Drinking Softened Water Harmful to Human Health?
The ion exchange softening process adds sodium at the rate of about eight mg/liter for each grain per gallon of water hardness. If the water is 30 grains hard, it will contain about 240 mg/liter of sodium — the same amount of sodium in two eight-ounce glasses of milk.
If softened water is used for cooking and drinking, the added sodium could be troublesome for individuals on sodium-restricted diets due to health problems such as hypertension.
While research indicates there is no proven cause and effect relationship between drinking softened water and hypertension, individuals following a sodium-restricted diet should discuss this matter with a physician.
When you don’t wish to use softened water for drinking and cooking, the simplest solution is to bypass the water softener with the cold water line to the kitchen. This provides hard water for drinking and cooking purposes.
Use of a separate “drinking water” faucet is done for aesthetic as well as health reasons. Many people prefer the taste of hard water to water that has been softened.
Will Using a Water Softener Damage A Septic Tank?
Water softeners have not been shown to have adverse effects on home waste water treatment systems. A University of Wisconsin-Madison study found that even when twice the average use rate of salt was discharged into the septic system, there was no difference in performance.
Consumer Guidelines for Purchasing a Water Softener
Use proven technology.
Buy a recognized brand from a dealer you know and trust.
Ask how long the company has been in business.
Ask how you can tell if the unit is working properly.
Check to see if the equipment has been validated or certified by a third party testing organization, such as the Water Quality Association (WQA).
Be sure you understand the cost of the system. Does the cost include installation fees? Are there extra charges for bypassing the cold water to the kitchen?
Be certain you understand the method and cost of regenerating the system.
Ask dealers for names of customers who have similar equipment. Check with the previous customers to see if they are satisfied with the equip ment and service.
Read the instruction book, keep it handy, refer to it often, and follow the directions.
Check the warranty provisions and send in the warranty card.
Have your water tested before and after installing equipment to evaluate the effectiveness of the treat ment.
The advantages of softened water are numerous. You can expect cleaner, softer-feeling clothes, less use of household cleaning products, less use of shampoo and other personal cleanliness products, and all-around easier maintenance and upkeep of the home. You also can expect longer life of appliances, including washing machines, dishwashers, and water heaters.
I couldent say it better myself