How They Work and Why You Need Them
In some parts of the country, water supplied to homes and businesses is affected by a condition known as hardness. This so-called hardness is, of course, not a condition one is able to feel but its effects inevitably become apparent in other ways. The term is applied to water that contains an unusually high concentration of minerals, particularly in the form of calcium and magnesium compounds. This tends to occur when the source water passes through layers of chalk and limestone present underground in certain areas. While its taste is largely unaffected, unless treated with a suitable water softener, its use for other purposes can pose problems.
The problems that can arise in hard-water areas are essentially twofold. First, these minerals tend to interfere with the normal ability of soaps to form a lather. As a result, it can be rather more difficult to wash one’s clothes, for example. While some newer detergents now possess the ability to overcome the lathering difficulties, the other consequence of living in a hard-water area is that the minerals tend to precipitate out and form a white film on taps and bath fittings, as well as forming a coating on the inner surfaces of kettles, geysers, and steam irons, which then acts to diminish their performance. Unless routinely employing water softeners, these appliances will need to be treated with special descaling chemicals on a regular basis.
Limescale in a kettle can be a nuisance, but it is hardly a disaster. In such cases, the build-up is visible and can be dealt with before it starts to become a problem. By contrast, should these deposits occur inside an industrial boiler, not only is there a risk of a breakdown that could lead to loss of production and profits, but it could actually result in an explosion and perhaps serious injuries to any personnel present in the vicinity. Whenever an industry may be required to rely on a supply of hard water for use in any of its processes, pre-treatment with one of the high-capacity water softeners designed for industrial use will be absolutely essential.
When the explanation for the hardness lies mainly in the presence of carbonates and bicarbonates, the resulting condition is a temporary one, and the simple act of boiling the water or adding a little calcium hydroxide is sufficient to reverse the hardness and to avoid any potential problems. However, when it is the sulphates and chlorides of calcium and magnesium that are present in the water, this gives rise to the permanent form of hardness and a more stringent form of treatment will be necessary to soften it.
To achieve this, water softeners work by exchanging any problem minerals present in the domestic or industrial supply with other elements that pose none of the problems brought about by hardness. The process involved is known as ion exchange and, most commonly, the replacement element of choice is sodium. Central to the process is a tank filled with small beads made from a polystyrene resin known as Zeolite and which carry a negative charge. When dissolved in water, the ions of calcium and magnesium carry a positive charge and, because opposite charges attract, these ions become attached to the beads and displace sodium ions present in the beads, because their positive charges are much weaker.
After a while, the resin contained in the water softeners become saturated with calcium and magnesium ions and can absorb no more. However, when flushed with a strong solution of brine, these unwanted ions will be washed away, allowing the resin to be recharged with sodium ions and ready to be used again. The hardness of water varies and there are kits with which to measure it, expressing the result in units known as grains per gallon (GPG) or alternatively, as milligrams per litre (mg/ℓ). Water containing up to 1 GPG is regarded as soft, while between 3,5 and 7 GPG it is classified as moderately hard and will require treatment. Once the level exceeds 7 GPG, however, it may be beyond the capacity of ion-exchange technology to soften it completely.
In practice, while hard water is not a health hazard, the increased level of sodium resulting from the softening process could pose a problem for someone with hypertension. However, there are alternative resins that make use of potassium chloride instead of salt. Talk to WaterIcon about a water-softening solution today.