Safe water means water that will not harm you if you come in contact with it. The most common use of this term applies to drinking water, but it could also apply to water for swimming or other uses, as H 2 O, but another way to consider the formula is HOH, where a positively charged hydrogen ion H + is bonded to a negatively charged hydroxide ion OH – . This means water has properties of both an acid and a base, where the properties essentially cancel each other out.
Safe water is the water which is the USEFUL WATER for any applications. Water should not contain arsenic, high fluorine , mercury & lead. There are a variety of trace elements present in virtually all potable water, some of which play a role in metabolism.
Safe water is the water which is even drinkable under 400 TDS, Also its pH less of 8. Rest of Water will be Hard. Hard water which does not give lather on soap solution. But soft make more soap lather once you mix.
Earlier The water is not Drinkable and useful to most of the applications .But its hardness is high makes plenty of softener needed to make more safe on applications to remove scales, pollutions, algae, bacteria.. after IWC its completely changed to soft.
The definition of a scale is an outer protective layer made up of flat, rigid, overlapping plates, in Water usage area its stated as Undissolved metallic salts embedded in inner surface of the water application area or line. May have very thick not removable by normal solvents.