There is now greater attention paid to product quality when items are being washed and hygiene as well as safety is given much more attention than perhaps even the customer appreciates. In general the amount of water available is reducing and its price increasing and we must use our technological skill to be as economical as possible with its usage. There is an increasing awareness of environmental conservation and we have a duty to conform with legislation regarding the quality and quantity of effluent we discharge into our sewers. The quality of raw water supplied by the water authorities is considered high in terms of purity for human consumption, but there are however, few waters which can be used for washing in laundry terms without some form of additional treatment.
Water falls in the form of rain, or snow, on to the ground soaking into it, or trickling over it, to form streams and rivers. On this journey the water comes into contact with many different types of rock formation, any of which may be water soluble. Water which flows very slowly, or stagnates, has an opportunity to dissolve other kinds of impurity, for example the products of decaying vegetation. From these examples it can be seen that no water that is available from natural sources can be said to be pure, although the presence of these impurities does not render it unfit for human consumption.
In terms of washing some of the impurities acceptable in drinking quality terms can have detrimental properties when applied from a laundry view.
Iron, or compound of iron, can be dissolved from certain types of rock and the effect in a washing process is to turn white items yellow and to produce discoloration on coloureds. In the case of woolens the yellow and discoloration can occur at very low levels of iron contamination. It is quite common to find naturally occurring soft waters containing iron, and this requires a special treatment or aeration and filtration. As the water is heated, any calcium and magnesium bicarbonates present decompose to form the carbonates and carbon dioxide. The impurities present in a water for laundry use are important from two points of view. In the first place they decide whether the water is suitable for use without treatment; if it is not, they also decide the kind of treatment that is required.
Hardness is probably the most important impurity. It is now generally recognised that the laundry use of water with a hardness greater than 6-7 degrees (100 ppm) is indefensible, both from the points of view of the quality of work obtainable and also of economy. All hard water can be softened, and the softening process always makes for real economy, since hard water causes such great waste of washing materials in the washing process. Hard water does not give a precipitate with synthetic detergents but it gives rise to a chalk-like loading with the usual laundry alkalis.
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