Difference between water softening and reverse osmosis system

14 June 2022 - water treatment

Commercial dishwashers: water softener vs reverse osmosis

When installing a commercial dishwasher or glasswasher in a pub, bar, restaurant or pizzeria, one of the first analyses to be carried out in order to avoid failures, is the hardness of the water that is supplied by the water mains and that will be used by the machine to wash and rinse the dishes and glasses.

The hardness of the water, along with its chemical and bacteriological composition, are the basic indicators of whether, and possibly which, water treatment system should be coupled to the dishwasher in order to ensure that it operates correctly and with maximum performance.

In professional washing, there are essentially 2 water treatment systems: the water softener and the reverse osmosis system.

But what are the differences between softener and reverse osmosis? How do these 2 systems work and what are they for? Can they co-exist?

These are important questions to answer because it is often thought that these 2 water treatment systems are synonymous, or that they perform the same task. Actually, although there are common points, these 2 technologies are based on different operating principles, providing different services.

Generally speaking, the main difference between the reverse osmosis system and the water softener is that while osmosis filters the drinking water, purifying it from any chemicals making it purer, healthier and safer, the purpose of the water softener is to lower the degree of hardness in the water.

Water softener: what it is and how it works

By its nature, drinking water used for domestic use or in public places is not chemically pure because it contains different types of substance: dissolved salts, minerals, organic compounds and glasses. In particular, salts dissolved in water are electrically charged (positively and negatively charged ions) and can be eliminated through the principle of ion exchange or deionisation.

The water softener applies exactly this principle of ion-exchange, which is able to change the amount of mineral salts in the drinking water, with the aim of lowering the hardness of the water and thus preventing the formation of limescale. The water softener is optional, both integrated and external for the entire hood type dishwasher range, while it is only external for all other models of glass washers and under counter dishwashers.

Limescale, also known as lime, is nothing more than a calcium and magnesium salt that, if present in high concentration in water, creates problems for both pipes and all the machines using water from that water supply system.

Ion exchange removes calcium and magnesium salts from water, replacing them with sodium salts, obtaining ‘softened’ water. This process takes place by passing so-called ‘hard’ water through a series of resins inside the softener. These resins are ‘loaded’ with sodium chloride, i.e. normal table salt. The salt is used as an ion exchanger and regenerator, gradually depleting during the process, requiring periodic replenishment with new salt.

Depending on the types of ions exchanged, the resins are called cationic or anionic. For water softening, cationic resins are used, i.e. resins that exchange + ions by binding to calcium (Ca++) and magnesium (Mg++) ions and exchanging them with the sodium ion (Na+). Sodium salts are non-fouling unlike calcium and magnesium salts.

Reverse osmosis system: what it is and how it works

Reverse osmosis technology makes it possible to improve the chemical, bacteriological and organoleptic properties of water in cases where mains drinking water has low quality.

Even if it is drinkable, in fact, water can be characterized by the presence of different pollutants such as nitrates, chlorine, herbicides, pesticides, microorganisms, organic pollution and residual pollution.

The reverse osmosis unit, e.g. the Osmo 180 osmosis unit, when coupled to the Unica range of dishwashers and glasswashers, forces water through a series of semi-permeable membranes, applying very high pressure to the fluid, which results in the generation of two solutions, thus separating high polluting water from pure water.

We can therefore define the reverse osmosis technique as the most refined and advanced water filtration technique thanks to the use of activated carbon filters and sediment filters.

Water softener or reverse osmosis system: which one to choose?

The choice of whether to install a water softener or a reverse osmosis system simply depends on the needs and problems encountered when installing a machine such as a professional dishwasher or glasswasher.

Is the problem the presence of hard water with a high limescale concentration? In this case, the ideal solution is to install an anti-limescale system such as a water softener.

Is there a problem with contaminants or high concentration of minerals in the mains water? The most efficient solution is the installation of a reverse osmosis system.

In general, these two water treatment systems offer a bar, restaurant, canteen or any other public place, the possibility of greatly improving the quality of mains water, allowing a professional dishwasher to be safely connected to the water supply. The advantages and differences are as follows:

Water softener:

  • is installed upstream of the plumbing system directly to the water mains, before any tap, appliance or machine that uses drinking water
  • produces softened water
  • reduces the possibility of breakdown of machines and equipment connected to the water mains
  • decreases the presence of limescale and corrosion of water system pipes
  • reduces the presence of limescale stains and spots when washing and rinsing dishes and glasses
  • reduces the concentration of chlorine and limescale in the water, making it healthier especially for those who are sensitive or allergic to these 2 elements

Reverse osmosis system:

  • is installed upstream of the dishwasher or glasswasher
  • generates purified oligomineral water
  • removes chemical, bacterial and mineral substances from water, improving its quality
  • improves the taste and smell of water
  • provides quality water, ideal for cooking, drinking and dishwashing
  • makes water clear and transparent
  • brighter glasses and goblets
  • less use of rinse aid and detergent
  • dish drying time significantly reduced to approx. 1 minute and 40 seconds* after taking the basket out of the machine. With the Unica 50Abt machine coupled with the Osmo180 system, the dishes are basically dry at the end of the cycle.

The ideal solution for water treatment?

Coupling a water softener, upstream of the water system, to a reverse osmosis system is the most recommended solution. With this type of system, in fact, limescale build-up in the membranes of the osmosis system is avoided, achieving lower energy consumption and high performance of the dishwasher and a significantly longer filter life.

If you would like a consultation to find out which dishwasher is best suited to your needs and what kind of water treatment system your business needs, please contact us and we will be more than happy to help.

Sistema Project Italia staff