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Measurement of Hardness in Water

Hard water is the term used to describe water that has minerals like calcium, iron, copper, and magnesium in specific quantities.

Hardness can be classified as carbonate and non-carbonate hardness. Carbonate hardness refers to calcium and magnesium bicarbonate and can be removed by boiling as it precipitates into solid and often referred to as temporary hardness.

Non-carbonate hardness is caused primarily by calcium and magnesium nitrates, chlorides and sulfates. Non-carbonate hardness is sometimes referred to as permanent hardness.

The amount of carbonate vs. non-carbonate hardness can be found by measuring alkalinity. If the alkalinity is equal to or greater than the hardness, all of the hardness is carbonate. Any excess hardness is non-carbonate hardness.

The levels of hardness are measured in grains per gallon (gpg), so water containing less than one grain is considered soft water. Slightly hard water would measure between 1-3.5 gpg, moderately hard 3.5 and 7 gpg, hard water 7-10.5 gpg, and very hard water would be anything higher than 10.5 gpg.

While it’s normal to have some level of these minerals in most water supplies, high levels can lead to following problems :-

Soap Scum

One of the most apparent issues with hard water is the presence of soap scum. Soap scum forms when the water evaporates, but the calcium deposits are left behind. Soap scum can be left on dishes, clothing, and surfaces in the shower. Clothing will look dingier and wear out faster. Towels will feel rough, and scum left on shower curtains can provide a breeding ground for bacteria.

Irritated Skin

Hard water will also cause problems for your skin and hair. The deposits left on the skin will dry the skin out and cause itchiness and other irritation. Children with eczema are especially sensitive to hard water. Hard water can also clog pores and coat the air, making it more prone to dullness.

Scale Deposits on Appliances and Pipes

Hard water deposits will eventually begin to build up on appliances that use water. The dishwasher, clothes washer, and hot water heater will all begin to suffer as sediment creates a scale that causes the appliance to wear out more quickly.


Hard water stains are reddish-brown stains that develop on porcelain plumbing fixtures.

Unpleasant Water Taste

The taste and smell of your drinking water can also suffer from hard water. It will often taste metallic if there’s too much iron, or there can sometimes be a rotten egg smell from the reaction between magnesium and some types of bacteria.


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