Frequently asked questions about a residential water softener


QUESTION: Will my family be deprived of minerals necessary to good health in drinking water softened by the ion exchange process?

ANSWER: No. Primarily the human body gains the minerals necessary to good health through eating foods not through drinking water. The body may absorb or use the minerals in water but, in most cases, the amount would not be significant. In order for a person to obtain significant minerals from water, it would be necessary to drink many gallons daily. In general, neither a water with a high mineral content nor a fully softened water could be considered a significant source of minerals. In contrast, one gallon of milk provides the mineral equivalent of a bathtub full of ordinary well water.

QUESTION: Is soft water safe for tropical fish?

ANSWER: Yes, soft water is satisfactory for most tropical fish. According to several authorities both fully soft water and municipally softened water would have no undesirable or toxic effect for use in an aquarium. When making the change from hard to soft water, it is necessary to make the substitution on a gradual stepwise basis of new water for old. This follows the basic pattern in regard to any change in the environment for tropical fish. This applies to temperature, pH of water, food as well as to hardness. Drastic changes, of course, would constitute a shock to the delicate systems of such fish and would result in fatalities. Preferably replace about one-fourth of the aquarium water at weekly intervals with soft water. Eventually, the aquarium will have a supply consisting of essentially soft water and the fish will suffer no ill effects as a result of the change.

QUESTION: Does soft water affect the operation of a humidifier?

ANSWER: Soft water provides for easier maintenance of a humidifier. When hard water is evaporated, the mineral residue consists of a hard scale which normally requires some drastic treatment (such as chipping or acid) for its removal. When soft water is used, the residue is commonly soft and can usually be removed by flushing the unit with water or by going over the surface with a brush. A point to remember: Softening water does not reduce the total amount of minerals present; ion exchange softening merely converts the calcium and magnesium minerals to sodium minerals. The humidifier most common in homes has an open pan, a small tube connected to a water source and float valve. When water evaporates, the float valve opens to permit makeup water to flow into the pan. Sooner or later, this type of unit fills with minerals deposited by the in-flowing water. If soft water is used in the humidifier, periodic flushing with fresh soft water will keep the mineral concentration down and, the unit will operate satisfactorily.

QUESTION: Can an ion exchange softener affect the removal of radioactive contaminants from water?

ANSWER: Yes, a water softener will remove approximately 80-90% of the radioactive substances likely to be found in water. If fed in proper concentrations, polyphosphates also control scale formation and corrosion in the ice cube machine. Approximately 5 ppm is recommended for scale prevention and 10 ppm for both scale prevention and corrosion control.

QUESTION: Does a water softener have any harmful effect on a septic tank?

ANSWER: The backwash and brining effluents from a softener can be discharged into a septic tank. The latter should, however, be properly installed and of adequate size to ensure satisfactory results. Proper sizing of the septic tank is highly important. While many states recommend units with a minimum of a 500 gallon capacity, even smaller units may provide adequate liquid capacity in relation to the amount of salts discharged by the softener. Many public health authorities recognize that softener regeneration wastes can be safely discharged into septic tanks. The Public Health Service in a "Manual of Septic Tank Practice" writes: "Waste brines from household water softener units have no adverse effect on the action of the septic tank but, may cause a slight shortening of the life of a disposal field installed in a structured clay-type soil." From this, it is evident that the type of soil in which the disposal field is situated must be taken into consideration. High concentrations of sodium salts deposited in certain types of soil over a period of time would result in loss of permeability. When this occurs, the soil cannot absorb and transmit the waste water. As a result, the absorption capacity of the drain field gradually decreases. On the other hand, the calcium and magnesium ions discharged by the softener may tend to open up the soil, reversing the clogging action of the sodium salts. To date, there are no reports on file of the failure of a distribution field to absorb the sodium salts due to softener regeneration wastes.In the event a serious doubt exists regarding the effect of the sodium wastes on the distribution field, the brine could be discharged into a dry well. Generally, a dry well (a hole filled with course gravel) will serve for many years. However, the use of a dry well should be necessary only in extremely few instances.There is some advantage in the use of fully automatic softeners where the discharge into the brine tank may be a problem. These softeners can be set to recharge frequently but, with smaller amounts of salt. Fully automatic softeners use from 40 to 80 gallons of water per recharging. With the operation requiring about one hour, the water flow rate is low. Further, the process is normally set to occur between midnight and 5:00 a.m., a time when little or no water is being used in the house. Under these conditions, a softener places far less burden on the capacity of the septic tank than do such water-using appliances as automatic dishwashers, washing machines or toilets, etc.

QUESTION: How can you calculate the amount of salt concentration in a septic tank?

ANSWER: If the liquid capacity of the tank is known, multiply the figure by 8.33 to determine the amount of water in pounds. If the liquid capacity is unknown, multiply the capacity in cubic feet by .80 (approximately 20% of the chamber will be filled with air at all times). Now multiply this figure by 62.33 to obtain the pounds of water in the tank. Compare the end figure (the total pounds of water) with the number of pounds of salt in the projected softener regeneration dosage. The pounds of salt should not exceed one percent of total amount of water in pounds in the tank.

QUESTION: Is the sodium in softened water harmful to people on restrictive salt diets?

ANSWER: Much depends on the strictness of the diet itself. Where the patient is on an extremely restrictive diet, he should drink neither hard nor softened water. Under these conditions, he should have demineralized water, distilled water or water known to be free of sodium for drinking and for the cooking of his foods. Such patients are commonly hospitalized. In establishing a salt-free diet for patients, physicians should not overlook the fact that even hard water may contain appreciable amounts of sodium. To determine the amount a complete analysis of the water is necessary.

QUESTION: How can the sodium content of a softened water be determined in terms of milligrams of sodium?


1. First, determine the sodium content of the natural water. Multiply the water's sodium content in grains per gallon expressed as calcium carbonate, by 7.866. This will give you the sodium content of the water in milligrams per litre of water.

2. Next determine the additional sodium content of water as a result of ion exchange softening. Here multiply the total hardness of the water in grains per gallon, expressed as calcium carbonate, by 866.
3. A simple addition of the results of both steps 1 & 2 will give the sodium content of the softened water in milligrams of sodium per litre. One litre (slightly more than a quart) is commonly accepted as normal water. Actually, the amount of sodium present in softened water is small when compared to the sodium present in foods.


QUESTION: How can iron stains be removed from fabrics?

ANSWER: Iron stains can be removed from most washable fabrics with oxalic acid, provided certain precautions are taken. Oxalic acid can be obtained at most drug stores. A solution of the oxalic acid may be made up by simply dissolving the crystals in water. The solubility of the acid is only about 10% so it cannot be made too strong. The solution should be prepared in an enameled or plastic container, never in a bare metal pail. A small amount of the solution should be tried on the inside of a hem or other inconspicuous location as the acid may bleach certain dyes. If, it is apparent that no bleaching has occurred, the entire garment may be repeatedly dipped in the solution. The dipping should continue until the iron stains are gone. Allowing the garment to soak in the acid solution is not recommended.  After the stains have disappeared, the garment should be thoroughly rinsed in several changes of fresh water. To be sure that any remaining acid has been neutralized, the garment should be immediately laundered in the normal manner with the regular amount of soap. The alkalinity in the soap will eliminate the last traces of acidity. The acid solution may be poured down the drain but it should be followed with a thorough flushing with fresh water.

However, there are several important reasons for not using a softener for this purpose. (1) It will only remove radioactive materials that are cationic in nature.

  • Further, it will achieve only partial removal (80-90%) of these contaminants. Now, depending on possible original concentrations, the removal of even 99% of radioactive materials may not make water safe to use or
  • Also, there is the problem of disposing of the radioactive ions into the sewage system. This would be a difficult, if not, an impossible

Discharge of radioactive ions into the sewage system is not recommended because of the disposal dangers. Burial of the contaminated softener after use is also not considered acceptable. Units utilized for removal of radioactive materials from water should be delivered to a central disposal site for proper handling. In view of the limitations of softeners, they cannot be recommended for reliable, positive decontamination. Because some radioactive substances are anionic while others are cationic, demineralization units employing strongly acidic cation resin and a strong base anion resin are necessary. Small "throw-away" demineralizers are available for emergency needs. Such units offer the most satisfactory solution to this problem.

QUESTION: Should softened water be used for watering house plants or for sprinkling the garden or lawn?

ANSWER: Where the amount of hardness minerals in the water is only moderate (less than 10 gpg); it is doubtful whether the sodium concentration would be sufficient to be a serious hazard to plants. Most house plants require specific soil conditions for healthy growth. Many thrive best in slightly acidic soils. If there is a high hardness concentration in the water being softened, the chances are good that necessarily high sodium concentration of the soft water would be harmful to plants. For outside sprinkling purposes, the use of softened water is first and foremost, wasteful. Again, where the concentration of hardness minerals is heavy, the sodium salts replacing them would definitely retard growth and might be sufficient to kill the grass.

QUESTION: Will soft water produce clearer ice cubes?

ANSWER: Actually, removing calcium and magnesium from the water has little effect on the quality of ice prepared in the home. Here again, the reason is that softening the water does not reduce the total mineral concentration. For example, to the extent that a softener removes sediment, iron and manganese from water, this would help to produce a least clean ice. Filters, of course, can be helpful in removing iron, turbidity, tastes and odors from water used for ice-making. The use of polyphosphates is an economical method of treating water used in typical restaurant ice-making units. The polyphosphates keep the minerals in the water dispersed and in this way minimize the cloudy appearance of ice cubes.

QUESTION: What general procedures should be used with household dishwashers?

ANSWER: In any case, the instructions of the dishwasher manufacturer should be followed. However, these may be supplemented with the following general considerations. Avoid the use of sudsing soaps or synthetic detergents as the suds which develop can "muffle" the spray action used in most dishwashers to provide scrubbing action. A number of washing compounds are on the market, which have been specifically formulated for dishwashers. Included are such brand names as Calgonite and Electro-Sol. These materials do not generally contain any soap - they depend upon the presence of greases and oils on the dishes to produce a cleaning solution. Even with the use of soft water, spotting of dishes is sometimes reported. In some cases, the cause may be traced to the use of too much washing compound or the use of the wrong material, as outlined above. In other cases, the dishwasher is loaded too heavily and improper cleaning occurs. Another common cause of spotting is too rapid drying. Ideally, the dishes should first be allowed to drain completely in a humid atmosphere so that the water with its minerals runs off, rather than evaporates. In some cases, the water temperature is too high and the water evaporates rather than drains. In other cases, the dishwasher lid opens at the end of the cycle and allows cool air to contact the utensils. This, too, results in rapid evaporation. Depending upon the construction of the dishwasher, it may be possible to adjust one or both of these factors to improve the results significantly.

QUESTION: Can softened water be used for a steam iron?

ANSWER: Neither hard nor soft water should be used with a steam iron. Demineralized or distilled water alone is acceptable for use over a period of time.

Remember, that the softening of water does not remove the minerals.

QUESTION: How much soap or detergent should be used in softened water?

ANSWER: When first using softened water for household cleaning chores, it is best to use as little soap as possible. If necessary, the homeowner can gradually increase the quantity to produce the desired results. The habit of using far too much soap is not easily broken. Therefore, anyone contacting the customer should stress the coffee measure as being adequate rather than the cup or more that may have been necessary prior to the installation of a water softener.

FAQ’s courtesy of the Canadian Water Quality Association (CWQA)