Water hardness: how to lower it in industrial dishwashers

25 May 2015 - Water hardness

What is water hardness and solutions
to lower it

The common user generally makes no distinction between rainwater and groundwater ( both flow into water reservoirs and then into our taps).
Rainwater is very soft water because it contains only traces of salts in solution.
Groundwater, on the other hand, can have different hardnesses depending on the layers of soil it flows through, the solubility of rocks and salts.
The difference seems trivial enough but is actually considerable; in fact, hard water causes nothing but difficultiesespecially when it comes to industrial dishwashers.

There are two types of water hardness used in industrial dishwashers:
1. Temporary hardness (also known as carbonate hardness)
2. Permanent hardness (or non-carbonate hardness)

Water hardness is measured in degrees (French and German degrees are traditionally the most commonly used).
A French grade corresponds to the content of hardening salts (calcium, magnesium, etc.) expressed as 10 mg/l of calcium carbonate.
In general, the following classification of water in relation to its hardness is generally used:

Soft water 10° F
Medium water 10-20° F
Hard water 20-30° F
Very hard water over 30° F

The drawback caused by hardness is the precipitation, i.e. the transformation of bicarbonates (soluble) into carbonates (insoluble). Precipitation becomes visible as it takes the form of a deposit (like the one formed inside a pot in which water has been boiled).
Temporary hardness is more troublesome than permanent hardness, since one of the main causes of its precipitation is heating, whereas permanent hardness does not cause precipitation after heating (boiling) and thus the salts it contains remain in solution.
The importance of low water hardness is more visible in the rinsing phase of the industrial dishwasher. Each drop of water, once evaporated and dried on a surface such as a plate or glass, leaves a hardness deposit on it in the form of insoluble calcium or magnesium salts.
Each wash cycle forms a new layer of salts, covering dishes and glasses with a mineral film and various stains.

Advantages for the dishwasher in lowering
water hardness

It is very important to connect the industrial dishwasher directly to hot water (every model of professional dishwasher and glasswasher made by Sistema Project Italia is already prepared for this type of installation).

This results in a significant energy saving due to the fact that the water flows into the dishwasher already at a certain temperature and in addition, considerably reduces limescale deposits on the heating element, inside the boiler and tank of the industrial dishwasher.
The combination of a good detergent and a rinse additive significantly reduces
the problems caused by hardness, however, in some cases and above a certain level of hardness, the only satisfactory solution is the use of a water softener.

On the other hand, the use of a reverse osmosis system is required, not to lower the hardness of the water, but in cases where the water that the dishwasher or glasswasher uses to wash and rinse the dishes needs to be purified of any chemicals, bacteria, organic residues or microorganisms.

Contact us to get more information about our industrial dishwashers, glasswashers and to learn about water softening solutions.

Sistema Project Italia Staff