What is "soft water"

Water \Wa"ter\ (w[add]"t[~e]r), n. [AS. w[ae]ter; akin to OS. watar, OFries. wetir, weter, LG. & D. water, G. wasser, OHG. wazzar, Icel. vatn, Sw. vatten, Dan. vand, Goth. wat[=o], O. Slav. & Russ. voda, Gr. 'y`dwr, Skr. udan water, ud to wet, and perhaps to L. unda wave. [root]137. Cf. Dropsy, Hydra, Otter, Wet, Whisky.]

1. The fluid which descends from the clouds in rain, and which forms rivers, lakes, seas, etc. ``We will drink water.''
   --Shak. ``Powers of fire, air, water, and earth.''
   --Milton.

   Note: Pure water consists of hydrogen and oxygen, H2O, and is a colorless, odorless, tasteless, transparent liquid, which is very slightly compressible. At its maximum density, 39[deg] Fahr. or 4[deg] C., it is the standard for specific gravities, one cubic centimeter weighing one gram. It freezes at 32[deg] Fahr. or 0[deg] C. and boils at 212[deg] Fahr. or 100[deg] C. (see Ice, Steam). It is the most important natural solvent, and is frequently impregnated with foreign matter which is mostly removed by distillation; hence, rain water is nearly pure. It is an important ingredient in the tissue of animals and plants, the human body containing about two thirds its weight of water.

2. A body of water, standing or flowing; a lake, river, or other collection of water.

   Remembering he had passed over a small water a poor scholar when first coming to the university, he kneeled.
   --Fuller.

3. Any liquid secretion, humor, or the like, resembling water; esp., the urine.

4. (Pharm.) A solution in water of a gaseous or readily volatile substance; as, ammonia water.
   --U. S. Pharm.

5. The limpidity and luster of a precious stone, especially a diamond; as, a diamond of the first water, that is, perfectly pure and transparent. Hence, of the first water, that is, of the first excellence.

6. A wavy, lustrous pattern or decoration such as is imparted to linen, silk, metals, etc. See Water, v. t., 3, Damask, v. t., and Damaskeen.

7. An addition to the shares representing the capital of a stock company so that the aggregate par value of the shares is increased while their value for investment is diminished, or ``diluted.'' [Brokers' Cant] Note: Water is often used adjectively and in the formation of many self-explaining compounds; as, water drainage; water gauge, or water-gauge; waterfowl, water-fowl, or water fowl; water-beaten; water-borne, water-circled, water-girdled, water-rocked, etc. Hard water. See under Hard. Inch of water, a unit of measure of quantity of water, being the quantity which will flow through an orifice one inch square, or a circular orifice one inch in diameter, in a vertical surface, under a stated constant head; also called miner's inch, and water inch. The shape of the orifice and the head vary in different localities. In the Western United States, for hydraulic mining, the standard aperture is square and the head from 4 to 9 inches above its center. In Europe, for experimental hydraulics, the orifice is usually round and the head from 1/2 of an inch to 1 inch above its top. Mineral water, waters which are so impregnated with foreign ingredients, such as gaseous, sulphureous, and saline substances, as to give them medicinal properties, or a particular flavor or temperature. Soft water, water not impregnated with lime or mineral salts. To hold water. See under Hold, v. t. To keep one's head above water, to keep afloat; fig., to avoid failure or sinking in the struggles of life. To make water.

   1. To pass urine.
      --Swift.

   2. (Naut.) To admit water; to leak.

      Water of crystallization (Chem.), the water combined with many salts in their crystalline form. This water is loosely, but, nevertheless, chemically, combined, for it is held in fixed and definite amount for each substance containing it. Thus, while pure copper sulphate, CuSO4, is a white amorphous substance, blue vitriol, the crystallized form, CuSO4.5H2O, contains five molecules of water of crystallization.

      Water on the brain (Med.), hydrocephalus.

      Water on the chest (Med.), hydrothorax.

      Note: Other phrases, in which water occurs as the first element, will be found in alphabetical order in the Vocabulary.

n. (context chemistry English) Water with a low concentration of dissolved minerals, especially calcium, making it easier to lather with soap.

n. water that is not hard (does not contain salts that interfere with the formation of lather with soap)

Soft water is surface water that contains low concentrations of ions and in particular is low in ions of calcium and magnesium. Soft water naturally occurs where rainfall and the drainage basin of rivers are formed of hard, impervious and calcium poor rocks. Examples in the UK include Snowdonia in Wales and the Western Highlands in Scotland.

The term may also be used to describe water that has been produced by a water softening process although such water is more correctly termed softened water. In these cases the water may also contain elevated levels of sodium and / or bicarbonate ions .

Because soft water has few calcium ions, there is no inhibition of the action of soaps and no soap scum is formed in normal washing. Similarly, soft water produces no calcium deposits in water heating systems. Water that is not soft is referred to as hard water.

Soft water forms lather with soap and does not form scum in much amount. It contains the normal salts required by the body.

In the UK, water is regarded as soft if the hardness is less than 100 mg/l of calcium carbonate. Water containing more than 100 mg/l of calcium carbonate is termed hard water. In the USA soft water is classified as having less than 60 mg/l of calcium carbonate.