What is a water filter and how does it work?

It is a device used to remove particles, chemicals, microorganisms, or other impurities from water, in order to improve its quality and make it safer for consumption, cooking, and other uses.

Water filters can be of different types, depending on their purpose and the level of cleanliness required. Some of the most common types of water filters are:

• Activated carbon filters: Carbon absorbs certain chemicals and removes chlorine, heavy metals, and other impurities that give an unpleasant taste and odor to water.
• Reverse osmosis filters: Reverse osmosis water filters are very effective in removing various harmful substances such as nitrates, lead, arsenic, chlorine, salt, heavy metals, and various common chemicals that may be present in water. They can also help reduce water hardness.
• Ultraviolet radiation filters: These filters use ultraviolet radiation to neutralize or remove bacteria, viruses, and other microorganisms from water.
• Particle filters: They remove large particles such as sand, rust, and sediment from water.
• Water softener filters: If there are problems with water hardness, these filters remove calcium and magnesium, replacing them with other ions, usually sodium.

Each of these filters works in a different way to improve the quality of water, but it is important to know what type of filter you need depending on your needs and the sources of pollution you may encounter in your area.

Criteria to consider before making your purchase

Water analysis

In order to make a proper filter purchase, it is good to have the ability to perform a water analysis to determine exactly what impurities are present in your tap water. Depending on the origin of the water and the area you live in, the final filter choice that will fully meet your need for clean water may vary. 

For example, water in Attica contains chlorine, in islands like the Cyclades there are many salts, and in other rural areas where it is not drinkable, it contains harmful substances for the body, such as heavy metals. Also, it is important whether the water comes from a public water supply or from a well. In the latter case, there is a possibility of contamination with bacteria such as E. coli and other microorganisms, as well as having elevated levels of nitrates due to pesticides.

Filter placement according to your needs

Water filtration devices are divided into categories depending on how they are connected: 

Countertop water filters: The device is placed on the kitchen countertop and is connected to the faucet, with a switch that allows you to choose between filtered or unfiltered water. It is easy to install even if you are not an expert.

Under-sink water filters with direct connection to the supply: The filter is placed under the kitchen sink and connected to the cold water supply of the kitchen faucet. It is an ideal choice if you have limited space on your countertop.

Whole house water filter: The filter is placed in the main water supply of the house (at the meters) and filters the water for the entire house.

For their installation, a plumber is needed.

Faucet filters: The filter is installed directly on the kitchen faucet and has a switch for filtered/unfiltered water, so you can wash dishes without using the replacement filter.

Water filter pitchers: The filter is placed inside a special pitcher and filters the water as you fill the pitcher. It is an economical solution that will improve the quality of the water you drink.

Shower water filters: It is connected to the input or output of the shower hose and helps reduce the amount of chlorine that comes into contact with our skin and hair. Additionally, it removes impurities and other pollutants from the water, such as lead, mercury, and other heavy metals.

Permeability (microns)

In water filters, the micron is a unit of measurement that describes the size of the pores through which water passes. The micron or micrometer is one-thousandth of a millimeter. The diameter of a hair ranges from 10 to 200 microns. Filters remove different pollutants depending on their micron rating. The smaller the micron rating, the finer particles are removed. The permeability level of the filter can vary depending on the type of filter and the degree of purification required for the specific water. Some filters can remove small particles, while others can remove smaller substances such as ions and molecules.

Water Flow

There are different types of water filters with different flow characteristics. Depending on your needs, you can choose the appropriate filter:

• Flow rate per minute: A higher capacity water filter allows for a higher flow rate per minute, which is useful for large families or household use.
• Slow filtration: Some filters apply slow filtration, allowing for a slower flow of water through the filter. This can improve the performance of the filter, as the water has more time to pass through the filtration medium.
• Fast filtration: Some filters provide fast filtration, allowing for faster water flow. This can be practical for cases where you need quick access to a large volume of water.
• Adjustable flow: Some water filters have the ability to adjust the water flow.
  • This allows you to customize the flow according to your needs and usage type.

  
  

  Filter capacity

  The capacity of a water filter refers to the amount of water it can filter or clean before it needs to be replaced or maintained. The capacity of the filter can depend on various factors, such as the type of filter, its size, the quality of the water it needs to filter, and the level of water pollution. To find what you need, you should consider the following:

  • Household needs: The daily water consumption is important in order to choose the ideal device. For a large family, a filter with a large capacity is needed.
  • Type of filter: The type of filter and the quality of the water it is intended for affect its capacity. If you live in an area with high levels of chemicals, metals, or other pollutants in the water, you may need to choose a filter with a higher capacity to cope with these challenges.
  • Frequency of replacement: Each filter has a different lifespan and needs to be replaced periodically. Check the specifications of the filter to determine how often it needs to be changed and choose a capacity that suits your needs.
  
  

  Filtration stages

  A water filter device can consist of more than one filtration stage that "work together" to remove various substances and particles from the water. The choice of the right filtration system depends on the water source and the specific needs of each user. The device may be equipped with different filters each filtering specific particles and substances from the water, resulting in a crystal-clear glass for you.

  
  

  Maximum operating pressure (bar)

  This refers to the maximum water pressure that the filter can withstand without being damaged or leaking. This is an important factor to ensure that the filter will operate effectively and safely under the manufacturer's specified conditions. The maximum pressure of the filter can be presented in various units of measurement, such as psi or bar.

  
  

  Maximum operating temperature

  Regarding the maximum operating temperature, it is the highest temperature at which the water filter can safely operate without being damaged or compromised.

  Excessive heat can affect the materials that make up the water filter and reduce its effectiveness or even destroy it.
  

  
  

  Spare Parts-Maintenance

  It is important to regularly check the spare parts of the water filter and replace them according to the manufacturer's instructions, so that the water filter maintains its effectiveness and provides clean water. Therefore, when making your purchase, you should also consider the cost of the spare parts you will need from time to time for filter maintenance.
  

  
  

  Easy Installation

  If you want to install the filter without the help of a professional, choose a filter that can be easily and quickly installed, without the need for special tools or plumbing knowledge. Additionally, check how easy it is to replace the spare parts to avoid any difficulties during maintenance.

  
  

  Lifespan

  The lifespan of a water filter depends on various factors, such as the quality of the water used, the frequency of use, the type of filter selected, and the capacity of the filter. Some filters, such as those for pitchers, may have a relatively short lifespan and need to be replaced every few months. Other filters, such as those designed for home water filtration systems, may last longer and need to be replaced every 6 months to 1-2 years, depending on the model and usage conditions.
  

  
  

  Certifications

  Water filters should have various certifications, both in terms of materials and functionality, which demonstrate that the product meets specific quality and safety standards.

  It is important to look for water filters that have the appropriate certifications to ensure their effectiveness.

  Some of the most common certifications for water filters:

  • NSF International (NSF): NSF certifies products that meet specific safety and quality standards for the removal of harmful substances from water.
  • Water Regulations Approval Scheme (WRAS): Independent British certification organization for plumbing products and materials.
  • Water Quality Association (WQA): WQA issues certifications for water filters that are tested for the removal of various contaminants, such as chlorine, lead, iron, etc.
  • American National Standards Institute (ANSI): ANSI is an organization that verifies product compliance with international standards.
  • WaterSense: WaterSense is a program of the U.S. Environmental Protection Agency that certifies products that contribute to water conservation.

  Search for these certifications or equivalent ones that water filters have, before deciding to purchase a product, to ensure it meets high standards of quality and safety.

  
  

  What else you need to know:

  When choosing a water filter device, you will see some features that will further assist you:

  • With replaceable filter: This means that an interchangeable filter or filters of corresponding compatibility are included with the device. Otherwise, you only purchase the filter housing device, check which filters are compatible, and choose the one(s) that will meet your needs.
  • With faucet: It includes an independent faucet that is installed on the countertop and connected to the device. Filtered water will flow from it.
  • Self-cleaning: A type of filter that cleans itself thanks to a special technology based on reversing the water flow, without the need to shut off the water supply. It only applies to central filters.
  • With pressure gauge: The device has an integrated pressure gauge used to measure the water pressure entering or leaving the filter system.
  This helps to see the performance of the filter and identify problems, such as excessively high pressure that could cause damage to the system or indicate the need for filter replacement

Common Mistakes to Avoid

• Choosing the wrong type of filter: Each filter has different advantages and limitations. Choose a filter that meets your needs, such as removing specific contaminants (e.g., chlorine, lead, heavy metals), reducing hardness, or improving taste.
• Buying a cheap filter with low performance: You definitely want an economical filter, but keep in mind that it may have low performance and may not effectively remove harmful substances from the water.
• Not following installation instructions: The installation of the water filter must be done according to the manufacturer's instructions. If not installed correctly, there may be water leakage or even a reduction in its effectiveness.
• Poor or no maintenance: Every filter has a specific lifespan and should be replaced or cleaned according to the manufacturer's instructions, within the recommended time. Over time, the pores can become clogged and filled with harmful substances. Thus, it begins to collect germs and bacteria, compromising the quality of the water and rendering it unsafe.
• Choosing an uncertified filter: It is important to choose filters from manufacturers that have certification from independent bodies. Certification confirms that the filter meets specific standards and requirements for performance and safety. Additionally, choosing a company with certified products ensures you receive proper service and the necessary spare parts.