Soft Water

“Soft water” is a term that describes water that has few or no magnesium and calcium deposits.  Igneous rock, like granite, and/or peat sources usually help produce soft water.  Sedimentary rocks are another source.  These items are normally low in calcium and magnesium.  Softened water, via the use of ion exchange, usually has more sodium ions than natural water.

Reverse osmosis treated water is considered “soft” because the majority of salt are removed.  However, the water will usually have hardness correction or need to be blended with hard water before being used in reticulation systems.  Soft water is void of substances that produce scum and scale.

Hard Water

Opposite of soft water, hard water contains high mineral content.  The minerals are usually calcium, magnesium, metal cations and, not very often, bicarbonates and sulfates.  Minerals can get into the water via limestone, chalk, and others.

The simplest way to determine if water is “hard” is to conduct a lather or froth test.  Get some toothpaste and/or soap and agitate it with the water.  If the water is hard, the toothpaste and soap won’t lather.

Even though hardness is mostly determined by the amount of calcium and magnesium, iron, aluminum and manganese can also be determining factors.

There are two types of hardness: temporary and permanent.

Temporary hardness is a combination of bicarbonate ions and calcium ions in the water.  The hardness can be removed with the use of boiling or by adding lime.  Permanent hardness is not able to be removed by boiling.  The hardness is usually caused by calcium and magnesium sulfates and chlorides in the water.  While permanent hardness can’t be fixed by boiling, it can be removed with the use of a water softener or ion exchange column.

Scaling, which is remaining mineral deposits, is caused by hard water.  After water has evaporated, limescale is left behind.  Limescale can cause pipe clogs, destroy water heaters, damage toilets and stick to the insides of coffee and tea pots.  Showering with hard water can leave hair rougher and more difficult to handle.  Since hard water doesn’t lather well with soap, a person may have a cleaner feeling after showering.

Boilers, cooling towers and other various pieces of water equipment are constantly being used to monitor water hardness in industrial settings.  To control hardness, chemicals and large-scale softening with zeolite and ion exchange resins are adding to the water.