What is reverse osmosis and how does it influence water quality?

Learn in the following article what a reverse osmosis filter is, when it is useful, and what other filtration systems you can choose from.

Water filtration systems relieve you of many concerns. Among the available water filtration systems available on the market, reverse osmosis systems are the most complex. But are they suitable for every household? Find out when reverse osmosis is useful and what other filtration systems are available to you.

• What is Reverse Osmosis?
• How it works and what a reverse osmosis water filter consists of?
• When a reverse osmosis system is useful?
• Other types of filters for drinking water
• Common questions

As the name suggests, reverse osmosis is the inverse process of osmosis. Therefore, to understand what this concept means, we must first clarify what osmosis actually is.

The term "osmosis" originates from Greek and means "to push." Osmosis is a biophysical process that involves the movement of water molecules through a semipermeable membrane, from a compartment with a low solute concentration to one with a higher concentration. This process works to balance the solute concentration on both sides of the membrane (1).

How does this process occur? High osmotic pressure restricts water from passing through the semipermeable membrane and is influenced by the amount of dissolved solutes. In the compartment where solutes are in higher concentration and water is scarcer, the osmotic pressure is also higher. This pressure pulls water into the compartment, thereby equalizing the solute concentrations between the two compartments (1).

Now that we understand what osmosis is, we can delve into the concept of reverse osmosis. The name indicates that the process is the reverse of regular osmosis. In reverse osmosis, water moves from a compartment with a higher solute concentration (and therefore higher osmotic pressure) to one with a lower solute concentration (and lower osmotic pressure). Because water naturally tends to migrate in the opposite direction to balance concentrations, external pressure must be applied to exceed the osmotic pressure of the more concentrated solution (1,2).
In simpler terms, a reverse osmosis system involves a complex water purification process that removes insoluble particles such as sand, rust, and clay; pathogens including microorganisms like viruses, bacteria, and parasites; and other contaminants such as microplastics, nitrates, nitrites, organic substances, heavy metals, and pesticides. Additionally, this system removes chlorine residues, which consequently eliminates unpleasant odors and tastes.

Reverse osmosis also removes calcium and magnesium salts. These substances increase water hardness and are responsible for limescale deposits inside coffee machines or other household appliances.

Following the filtration process through reverse osmosis, a large portion of the bioelements in the water can be removed, depending on the consumer's preferences. Although the water resulting from this process is safe for consumption, a water remineralization filter can optionally be added.

Over time, reverse osmosis pumps have been primarily used for industrial or laboratory purposes (2). Industrial reverse osmosis can be applied in various fields where superior water quality is required—for example, in the pharmaceutical and cosmetic industries, car washes, or horticulture.

A reverse osmosis filtration system consists of several components that ensure water purification:

1. Pre-filtration

Initially, the water passes through a conventional filter, such as a sediment filter, which retains solid suspensions (like sand) and other impurities. This process protects the reverse osmosis membrane (4).

2. Application of external pressure

A reverse osmosis station is also equipped with a pressure pump. Thanks to this pump, the water achieves the necessary pressure to pass through the osmotic membrane (4).

3. Filtration through the osmotic membrane (reverse osmosis membrane)

The reverse osmosis membrane has a typical thickness of 0.05 mm and is semi-permeable. It has a dense structure with very small pores that enable the separation of water molecules from the dissolved substances. This membrane can retain up to 99% of dissolved substances while allowing water to pass through (2).

4. Remineralization filtration

This stage restores the mineral composition of the water. However, the remineralization filter is optional, as the water resulting from reverse osmosis is already suitable for consumption.

 

In what situations is it recommended to install a reverse osmosis water filtration system in your home? This system is useful when you want to remove certain components from tap water, even if some are within acceptable limits. Moreover, along with other elements, chlorine is also eliminated from the water. This way, the water obtained through the reverse osmosis filtration process is suitable not only for drinking but also for cooking or even washing vegetables and fruits.

Additionally, reverse osmosis is a solution for obtaining potable water in areas where the only water sources are marine water or other waters with a high level of mineralization (2).

Some of the water filtration systems you can install in your home include:

• Sediment filter: This filter mechanically purifies tap water by trapping impurities such as sand, rust, clay, and other solid particles present in the water. The variety of impurities retained depends on the pore size of the filter. Ultrafiltration filters, with pore sizes of 0.2-0.45 microns, even eliminate bacteria and viruses.
• Activated carbon filter: Activated carbon has adsorbent properties, meaning it accumulates substances from the water such as chlorine, volatile organic compounds, iron, and manganese, thereby reducing unpleasant tastes and odors. This filter is used in combination with the sediment filter, as solid particles need to be removed before the water passes through the activated carbon filter.
  
  Activated carbon has adsorbent properties, meaning it accumulates substances from the water such as chlorine, volatile organic compounds, iron, and manganese, thereby reducing unpleasant tastes and odors. This filter is used in combination with the sediment filter, as solid particles need to be removed before the water passes through the activated carbon filter.
  
  This type of filter is also available in our product portfolio. La Fântâna provides the Sistemath Duon water filter, which is installed under the sink and connected directly to the cold-water tap. The system’s advantage is that the water filtered through it retains its natural mineral content and taste. Additionally, it helps significantly reduce plastic consumption. Discover more details here:Potable Water Filters SISTEMATH DUON.
• Anti-scale filter: This is an alternative to the water softening filter. Unlike a water softening filter that reduces water hardness, the anti-scale filter prevents deposits on installations without altering the water’s hardness. It contains polyphosphates that transform calcium and magnesium carbonates into a soluble substance that does not easily deposit on pipes. The anti-scale filter is ideal for coffee machines, as retaining these minerals in the water enhances the authentic taste of coffee.

By choosing La Fântâna, a trusted partner with extensive experience, you will benefit from durable and efficient solutions for water filtration and treatment. Our specialized technical team handles the installation and regular maintenance of the equipment, ensuring you constant access to the highest quality water, without any worries on your part.

Below, discover answers to some of the most common questions about reverse osmosis water filtration systems.

1. Does reverse osmosis have disadvantages?

There are a few aspects to consider when choosing such a product. First, you need a dedicated space. Additionally, you should be aware that it removes a significant portion of the minerals present in the water (which may lead to a different perception of the water's "taste"). For this reason, our range of reverse osmosis water filtration systems includes an optional remineralization filter.

2. What is required to maintain a reverse osmosis drinking water filtration system?

Typically, depending on the water purifier model you choose, the filter cartridges are the components that require the most frequent replacement due to the high concentration of calcium and magnesium in the water, excessive chlorine, or visible impurities such as sand and rust.

However, if you choose a reverse osmosis filtration system from the La Fântâna catalog, our technical team ensures both installation and the necessary periodic maintenance, so you don’t have to worry about various filter replacements for reverse osmosis.

3. What are the risks associated with using a reverse osmosis filtration system in homes with old pipes

The presence of particles and sediments in old pipes can decrease the efficiency of the filtration system, leading to the need for more frequent filter replacements. This is why the installation of La Fântâna reverse osmosis equipment is always carried out with a sediment filter that mechanically filters tap water, retaining impurities such as sand, rust, clay, and other solid particles commonly found in old pipes.

4. When should I use a reverse osmosis water filter with a pump?

Considering that a reverse osmosis filter with a pump is a water purification system that uses an additional pump to increase the pressure of the supply water entering the reverse osmosis unit, such a filter is ideal to use when water pressure is low. This ensures enhanced efficiency and performance of the reverse osmosis system.

Therefore, reverse osmosis is a highly effective filtration method. However, consider all types of filtration systems to determine the one most suitable for your needs. With their help, you and your family can enjoy high-quality network water without exposing yourselves to health risks.

Photo sources: Shutterstock.com, LaFantana.ro

References:

1. Lopez, Michael J, and Carrie A Hall. “Physiology, Osmosis.” Nih.gov, StatPearls Publishing, 13 Mar. 2023, www.ncbi.nlm.nih.gov/books/NBK557609/. Accessed 3 July 2023.
2. World Health Organization. Sustainable Development and Healthy Environments Cluster. (‎2005)‎. Nutrients in drinking water. World Health Organization.
3. Isha Shrimanker, and Sandeep Bhattarai. “Electrolytes.” Nih.gov, StatPearls Publishing, 23 Apr. 2023, www.ncbi.nlm.nih.gov/books/NBK541123/. Accessed 3 July 2023.
4. M, Garud R, et al. “A Short Review on Process and Applications of Reverse Osmosis.” ResearchGate, 2011, www.researchgate.net/publication/236002547_A_Short_Review_on_Process_and_Applications_of_Reverse_Osmosis. Accessed 3 July 2023.