Complete Guide On How To Detect, Test & Treat Hardness In Water

Have you ever wondered the cause behind soap forming unexpected lather or scum, or why does water leave stains on windows and cars on drying? Check out the comprehensive guide to understand the cause behind them and the hardness in urban water.

What Is Hardness In Water ?

Be it formation of lather or soap scum with soap and water or the stains that are left behind by water on drying, all are indicative of the presence of hardness in water. Hardness in water is observed due to the presence of dissolved minerals like calcium and magnesium in high quantities in it. Minerals like calcium on reacting with soap forms 'soap scum' instead of bubble lather. This 'soap scum' is of no use in cleaning and washing. Hence more soap or detergent is used to perform the same task than that would have required using soft water. 

Hard water behave differently as compared to water with low levels of such minerals or soft water. These minerals makes it difficult to use water for effective cleaning and washing.

Hard water

Soft water

Rich in minerals like calcium and magnesium

Contains less minerals mostly cations and that too Sodium ions

Tastes better and is healthy for daily intake 

Tastes salty ( if processed for water hardness) otherwise have little taste due to lack of minerals  

Soap scum formed on reaction with soap

Bubble lather formed on reaction with soap which is good to use

Poor cleaning and washing

Effective cleaning and washing

Hard on skin and hairs

Good on skin and hair

Water stains are left behind on window panes, glass

Leaves no stain whatsoever on drying 

Damages water supply pipelines by depositing minerals like calcium as 'scales'.

No damage whatsoever to the water supply pipeline

Depending on the type of mineral in water, hardness can be classified into two main types: 

Temporary Hardness

Permanent Hardness

Bicarbonate Minerals as in Calcium Bicarbonate and Magnesium Bicarbonate

Sulphate and chloride compounds such as calcium sulphate, magnesium sulphate and calcium chloride and magnesium chloride

Boiling removes temporary hardness

No effect on Boiling

Water softener removes hardness completely

Water softener removes hardness completely

Why Analyze Hardness For Water Quality ?

Minerals like calcium and magnesium present in hard water could damage the water supply pipeline and faucet. Over a course of time these minerals gets deposited in the pipelines forming 'scales'. This scale is an insulating coating which ultimately choke the flow of water through the pipeline. This could reduce the entire household water pressure. The scales being insulating in nature, hence hard water also adversely effects the electrical equipments.

Hence it is important to know your water.

Hard water is not a threat to human life if consumed. Instead the minerals in it like calcium and magnesium is helpful in maintaining our daily body functions if consumed in optimum amount.

But hard water on skin and hair is a different story altogether. It leaves them dry and is not recommended for bathing.

Note: If your water supply has high concentration of manganese and iron you might want to check the arsenic in your water supply. 

Sources Of Water Hardness

Water is called a universal solvent because of its ability to dissolve a large number of elements. Water on reacting with the carbon dioxide forms a weak carbonic acid. Carbonic acid is even a better solvent than water. When water under pressure flows in rivers, it passes through many types of rocks and soil. During this process minute quantities of calcium and magnesium gets dissolved in water and is carried away to our urban water supply.

The reaction between water, carbon dioxide and calcium carbonate results into:

     CaCO3  + CO2 + H2O ⇌ Ca2+ + 2 HCO3

The end products are free Calcium ion cations and weak carbonic acid. This release of free calcium ions increases the level of calcium in water. Thus hardness level increases in water along with the level of Calcium.

Urban Water Hardness Standards

U.S. Department of Interior and the Water Quality Association categorize hardness level for water as shown below :


Hardness level (mg\L)

Soft Water

0 - 17.1

Slightly Hard water

17.1 - 60

Moderately Hard water

60 - 120

Hard water

120 - 180 

Very Hard water

180 and above

The standard for the hardness level may differ slightly for different guidelines issued by many organizations but the standards remain more or less the same.

Operations : Detect, Measure, Test & Treatment



It is impossible to distinguish between hard and soft water with naked eye for there is no change in color.

However, instead of looking for a color indication in water sample, its best to look at the supply pipelines and faucets. If you find a depository white powder lining your water supply equipments then it indicates the hardness in your water supply.


No distinct odor is observed in either hard or soft water.


Unit Of Measuring Hardness In Water

Hardness in water is generally expressed in milligrams of minerals present per litre of water or mg\L . PPM or parts per million is another unit used to express the same.


Check out the hard water tester at amazon

Urban Water Treatment

Water could be treated for hardness in the following ways depending on the type of hardness they possess:

Water Softening System involves the use of water softeners. Water Softeners removes the minerals responsible for hardness through the ion exchange method. The water containing dissolved Calcium (Ca2+) and Magnesium (Mg2+) are made to pass through a resin bed. This resin bed contains Sodium (Na1+) which has a lower positive charge than Calcium. Hence calcium reacts with the resin replacing Sodium which in turn reacts with excessive chlorine in water to form sodium chloride (NaCl) salt. Thus the cations responsible for hardness are removed from water. Soft water is hence obtained.

However the sodium in the resin bed should be frequently reinforced to make up for the depletion.

Check out the Water Softening System. Before selecting a mechanical water softener check out the hardness, iron and manganese levels in your water supply. 



Minerals like Calcium and Magnesium are not a threat to the aquatic plants and animals. 

In fact calcium is known to be a building block in many marine habitats. For Instance the deposition of calcium carbonate by coral organisms over the years have resulted into formation of some of the majestic sites such as the Great Barrier Reef.


Hard water is a nuisance when it comes to cleaning and washing. It reacts with soap to form scum thus hindering effective cleaning. On drying hard water leaves behind white stains on glasses, cars etc.

Bathing with hard water is not recommended for it will leave the skin dry. It also affects the hairs and they appear rough on drying.

But not all is bad with hard water. It provides body with calcium and magnesium which is important for metabolism if taken in appropriate quantity. Again high levels of calcium intake through drinking could result into formation of kidney stones. Excessive intake of magnesium may affect the kidney and the bowel movements. So check out the hardness in water.

Also make sure to limit the sodium intake in water.

Household water equipment : Regular maintenance of household pipelines and faucets is required to remove the 'scales' formation. It is formed due to deposition of minerals like calcium and slowly will choke down the pipeline and the water force.