Hardness results from the presence of lime and magnesia dissolved in the water.
Temporary hardness," which is removed by boiling, is due to carbonates, " permanent hardness " to sulphates of lime and magnesia.
Hard water is readily detected by its behaviour with soap.
Every householder knows how with certain waters the soap precipitates in flaky particles before it is possible to produce a lather. This means that part of the soap is used up in softening the water, or, in other words, that there is a daily waste of soap.
It is also unpleasant for domestic use, causing roughness of the skin and " chapping " in winter, and is a fruitful cause of many bodily derangements, including dyspepsia, glandular swellings, gout, and rheumatism.
Every grain of lime per gallon of water constitutes one degree of hardness, and it has been laid down by authorities that no public water supply should exceed 10 degrees.
When this is exceeded it is worth while to instal a softening apparatus in connection with the domestic system. An efficient water softener may be purchased at from 10 to. £25 and upwards, according to the size of the household. It consists of a separate cistern in which a certain definite amount of " anticalcaire," or other softening agent, is introduced automatically into the water as it leaves the main, and a filter system for intercepting the limy deposit which results. Well water may be similarly treated if forced into a cistern before use.