[katie]

Please could you urgently explain about the hardness of water, i know i have asked this before but i just dont get it!

[mike]

Did you read the answers to the last time you asked this question?

[BaliG]

Hardness is based on the amount calcium and/or magnesium ions in water.  To tell whether the water sample you are testing is hard or not is too add soap to it.  If it readily forms a lather then the water sample is soft however if it forms a grey scum (ie a Mg/Ca stearate precipitate) the water is hard.  To test for the amount of Magnesium and Calcium ions are solution you can titrate it with EDTA.  Hardness causes a fair few problems mainly causing scaling of electrical appliances such as kettles and making it unsafe for human consumption. To cure hardness use a water softener which usually contains Calcium Chloride.

[Borek]

Hardness is based on the amount calcium and/or magnesium ions in water.

Here I agree...

To cure hardness use a water softener which usually contains Calcium Chloride.

Are you telling us that to cure water hardness based on the presence of Ca²⁺ you have to add more Ca²⁺ to water?

Hardness causes a fair few problems mainly causing scaling of electrical appliances such as kettles and making it unsafe for human consumption.

Can you elaborate on the "unsafe for human consumption" statement? Most mineral waters - both sold as beverage and used in therapies - are highly mineralised and hard. I doubt they are dangerous for your health.