Water Hardness is the concentration of mineral compounds that exist in a given amount of water. It is a measure of the quantity of divalent ions (for this discussion, salts with two positive charges) such as calcium, magnesium and/or iron in water. There are many different divalent salts; however, calcium and magnesium are the most common sources of water hardness. Water referred to as “hard” commonly has a high concentration of such salts and the “soft” water contains very little of them.
Hardness is traditionally measured by chemical titration. The hardness of a water sample is reported in milligrams per liter (same as parts per million, ppm) as calcium carbonate (mg/l CaCO3). The unit of measurement of the hardness that is used most commonly are hydrometric French degrees (° HF), and the calculation of this parameter corresponds to the following formula:
(mg/l ca x 2.5 + mg/l mg x 4.2) / 10
How Is Hard Water Generated?
The presence of calcium and magnesium salts in water depends mainly on geological formations water has to pass through prior to its collecting. Groundwater which cross carbonate (limestone) aquifers are those with higher hardness; these aquifers are composed of calcium and magnesium carbonates.
Groundwater from aquifers of eminently silicate composition, for example granite, contribute to soft water, this means, water with very low amounts of calcium and magnesium salts.
A very visible impact in the waters of different hardness -“hard water” and “soft water”- is their different behaviour to the addition of soap. In the incidence of the same amount of soap, foaming is smaller in the case of “hard” water, because calcium and magnesium react with the compounds which form soap and stop working, with the consequent need to add more amount of soap.
The best known effect in places where the water supply has a high hardness is the lime scale formation, commonly referred to as lime.
It is important to know the hardness of the water supply in your town, since this figure allows us to adjust the operation of certain appliances that offer this possibility (particularly washing machines and dishwashers). This prior regulation to the electronic appliances allows changes in the operation thereof it depending on the set value and thus the negative effects that high water hardness may cause, resulting in better performance and longer duration of the machines.
It represents a series of fouling problems in industrial and domestic equipment
Classification of Water Hardness (H ° F):
– <7: very soft water
– 7-14: soft water
– 14-32: intermediate water hardness
– 32-54: hard water
-> 54: very hard water
There has not been set a limit for this parameter as the World Health Organization determined that whether the water hardness is high or low, these values don’t have a toxic effect on the health of people.
There is some evidence of lower cardiovascular disease rates associated with hard water areas than in areas where the water supply is soft.
An adequate daily intake of calcium is essential for normal growth and health. Foods such as dairy products, beans, eggs, nuts, cauliflower and spinach contain calcium.