The common user in general makes no distinction between rainwater and groundwater (both
flow into the water-sheds and thereafter into our taps).
Rainwater is a very soft water because it contains nothing but traces of salts in solution.
Groundwater instead has widespread hardness depending on the layers of ground through which it passes and the solubility of the rocks and the salts.
The difference seems relatively banal, but it is actually significant;
Indeed hard water can cause difficulties, especially to commercial dishwashers.
There are two types of hardness of the water :
1. Temporary hardness (also known as bicarbonate hardness):
2. Permanent (or non carbonate) hardness.
The hardness of water is measured in degrees (commonly French and German).
One French degree corresponds to the content of hardening salts (calcium, magnesium, etc.) expressed as 10 mg of calcium carbonate per litre of water.
The following classification of water in relation to its hardness is the most recognized :
Soft water 10° F
Medium water 10-20° F
Hard water 20-30° F
Very hard water, over 30° F
The trouble caused by the hardness is due to precipitation, i.e. transformation of the bicarbonates
(soluble) into carbonates (insoluble).
Precipitation is visible since it takes the form of a deposit (like the crust that develops inside a pan in which water has been boiled).
Temporary hardness is the most troublesome, since one of the main causes of precipitation in this case is heating, whereas there is no precipitation after heating (boiling) with permanent hardness and the salts therefore remain in solution.
Water hardness becomes crucial during the rinse phase.
As each drop of water dries on a plate or a glass, it leaves a hardness deposit in the form of insoluble calcium or magnesium salts. Every cycle forms a new layer of these salts, so in this way dishes and glasses are soon covered with a mineral film or various marks.
It is extremely important to connect the machine directly to the hot water tap ( every commercial dishwasher by Sistema Project Italia is compatible with this function ).
That causes a remarkable power save for water heating and, on top of that, reduces alot the deposit of limestone on the heating element, on the inside of the boiler and on the wash tank of your commercial dishwasher.
The combination of a good detergent and a good rinse-aid considerably reduces the problems caused by water hardness.
In some cases, however, over a certain degree of hardness, the only satisfactory solution is to
install a water softener.
Sistema Project Italia Staff