What is Hard Water? Hard Water vs Soft Water

Hard water is caused when there are dissolved salts of Calcium and Magnesium in the water. The origin of the term ‘Hard Water’ is believed to have just evolved in the 19th centaury due to the fact that it was difficult or 'Hard' to wash clothes, because soap will not bubble or lather in hard water. Soft water on the other hand makes soap lather easily and thus washing clothes are easy.

Soap is a Sodium salt of the Fatty Acids obtained from oils like coconut oil. The Sodium in the soap gets replaced by Calcium in hard water and results in an insoluble deposit called 'Scum'. When bathing in hard water, it feels sticky because this scum is deposited on the body and hair. Another problem with hard water is that the hardness salts (Calcium and Magnesium) gets deposited as a scale inside water pipes and thus reducing its diameter. Eventually it can severely restrict the flow in water pipelines and may even block it. Water heaters gets scaled with hard water. Sometimes the water heater can get completely blocked with scales and this is dangerous. Always make sure that the flow through the water heater is not restricted.

Hard water is not good for any cleaning work. Clothes washed in hard water look crumbled and feels stiff and scratchy. Dishes and glasses washed in hard water looks dull when dried due to a film deposit of the hardness salts. Soft water on the other hand is good for all of the above work.

Drinking Hard Water

Drinking Hard Water is not harmful to health - The World Health Organization says that "There does not appear to be any convincing evidence that Water Hardness causes adverse health effects in humans". But as mentioned before hard water causes Scaling and sometimes makes Coffee and Tea change colour and taste. It is also believed that hard water can be bad for skin diseases like eczema. Hard water is alkaline water and it is believed that drinking alkaline water is good for health.

Hard water can be ‘softened’ by replacing the Calcium and Magnesium ions with Sodium Ions in an Ion Exchange Water Softener. Such softened water or soft water will contains Sodium salts instead of the Calcium and Magnesium. This water may not be advisable for drinking by people with high blood pressure, since they should follow a sodium restricted diet. For washing clothes, treating the hard water with Sodium Carbonate or Washing soda, reduces many of its problems.

RO or Reverse Osmosis is a good treatment to get rid of hardness in water. A new membrane technology called Nanofiltration is becoming used more and more in the softening of water. We have a dedicated page on RO and Nanofiltration.

Hard water is found in areas where there are chalk and limestone in the landscape or geology. As water passes through these chalk and limestone it dissolves Calcium Carbonates and Bicarbonates and makes the water hard.

Water Hardness Units and Measurement of Water Hardness

There are many types Water Hardness Measurement. Water Hardness Measurement is usually in parts per million (ppm) of Calcium Carbonate equivalent. The most common Water Hardness Units of measurement in India is in parts per million (ppm) of Calcium Carbonate equivalent. In the USA the Water Hardness Units are in Grains per Gallon (gpg). 1 gpg = 17.1 ppm. Different parts of the world have different Water Hardness Measurement or Water Hardness Units as you can see from the following table.

From the above table, water containing about 75 milligrams/litre or less of Calcium Carbonate equivalent (the most common unit of measurement of hardness in India) is considered soft water. At 250 mg/L it is hard water and 350mg/L is considered very hard water.

As mentioned before hard water is drinkable and is not harmful to health. But having a bath in hard water feels sticky and we do not get that fresh feeling of having had a bath.

To make Hard Water Soft for domestic use, a water softener has been the traditional method in advanced countries of the world. This is a process of ion exchange using special resins and replacing the Calcium and Magnesium ions with Sodium ions. Sodium Chloride or common salt is used for for water softening to regenerate the ion exchange resin. Reverse Osmosis or RO removes all the Calcium and Magnesium from the water and there is no need of adding any Sodium to the water. To get the full benefits of Soft water, the water in the whole house must be softened. Most people use RO only for drinking water purification of hard water.

Drinking Hard Water is not at all harmful to health. There is school of thought that drinking hard water, which is alkaline water, is beneficial to health, because of the mineral Calcium and others it contains. Where you really need soft water is to have a bath, to do your laundry and wash dishes. For this you must think of softening the water for the whole house. The latest and the most efficient Salt Free Water Softener is a Nanofiltration unit for your whole house. Nanofiltration is explained in more detail on our page on RO & NanoFiltration . Nanofiltration and Reverse Osmosis are both Salt Free Water Softener Systems to remove Water Hardness.